Windows

1. Navigate to Norton's update center. Click the yellow 'Update Me Now' button. This button will scan your existing installations of Norton software and take you through the update process. Follow all on-screen instructions provided. You may need to restart your computer.If the ccsvchst.exe errors cease after Norton has been updated, you do not need to take any further steps.
2. Uninstall Norton Antivirus from your computer. Open the Start menu and click on 'Control Panel.' Click 'Programs.' Highlight the Norton product from the program list displayed. Click 'Uninstall.' Follow any on-screen instructions as prompted.

3. Run your registry cleaner software. This will erase any last traces of uninstalled software from your system. If the errors cease, reinstall the program using the latest version available on the Norton website. If the errors continue after this step has been taken, there is likely a spyware program or virus posing as ccsvchst.exe. Continue to step 4.
4. Launch your anti-spyware software. Perform a full scan of your hard drive. Follow the on-screen instructions to quarantine and remove any malicious software that is detected. Once your hard drive is clean, you may safely reinstall Norton.

1. Understand the causes of missing NTLDR errors. One of the most common reasons for an NTLDR-based startup error occurs when Windows XP attempts to start from a hard drive that isn't set up to launch Windows XP. For example, you may encounter an NTLDR error if you attempt to boot from an improperly formatted Windows XP startup disk. These errors may also be caused by corrupt, missing hard drive data and loose hardware cables.
2. Click the Start menu button in the lower left-hand corner of the Windows XP screen. Select 'Restart' to reboot the PC.

3. Check that the computer's optical media drives are empty. A major cause of NTLDR errors is when a non-startup disk is in the CD slot and Windows XP attempts to launch from it.
4. Insert the Windows XP installation disk. Restart the computer. Press any key on your keyboard during the startup process to launch the installation setup screen. Press the 'R' key on your keyboard when the Windows XP Setup screen appears. This launches the Windows XP Recovery Console program and a screen in which you can type command prompts.
5. Type 'copy d:\i386\ntldr c:\' (without quotation marks) in the command prompt window, then press the Enter key on your keyboard. Type 'copy d:\i386\ntdetect.com c:\' (without quotation marks), and press the Enter key again. The Windows XP Setup software will detect and replace any NTLDR software files that may be missing or corrupt.
6. Press the 'Y' key on your keyboard if the Windows XP Setup software asks for permission to rewrite and replace the files in Step 5.
7. Eject the Windows XP installation disk by pressing the Eject button on the front of your computer. Type 'exit' (without quotation marks) in the command prompt window to close the Setup software, then press the Enter key on your keyboard to restart the PC. Windows XP will now launch without missing NTLDR errors.

1. Restart your computer. Software conflicts may arise during day-to-day usage that causes a network error, thus provoking a NAT error. Restarting clears the system cache and may fix this error.
2. Close any networking devices and programs that use a heavy data connection. For example, bitTorrent clients such as Vuze or Azureus are notoriously common causes of NAT errors. If shutting down the bitTorrent file sharing software and similar network-intensive programs does not fix your NAT error, continue to Step 3.

3. Open your firewall software's preferences options. Check the level of security at which the firewall is currently operating. Some firewalls set a default security level that is too stringent and prevents legitimate software from accessing the network, thus causing NAT errors. Check that the firewall is allowing legitimate traffic and has not closed all of your computer's ports.
4. Reset your Internet or local network router. Use a paper clip or pen point to press the recessed reset button on the back of the device. Hold down the reset button for 10 to 20 seconds until all of the lights on the front of the router flash. Release the reset button and wait for your computer to reconnect to the network.

1. Click 'Start' and then 'Control Panel' and go to 'User Accounts.' See if you have administrative privileges. If you do not, restart the system and log-in as administrator.
2. Check whether you have the latest version of Windows installer on your system. To find the version of Windows installer go to the 'System32' folder in the Windows directory and find the file 'MSI.DLL'. Right-click on it and go to 'Properties' and check the version. If the version is older than 3, you need to update the installer.

3. Download the latest version of Windows installer from microsoft.com and install using default options. A link to the download is in the Resources section of this article. Restart your system and log in as administrator.
4. Go back to the 'System32' folder and check whether the 'MSI.DLL' file is updated to the latest version.
5. Install the desired software with administrative rights. If Error 1406 still occurs, the problem is due to a bug in the software. Download a different version of the software and proceed with the installation.

1. Click \'Start,\' then click \'Run.\'
2. Type \'regedit\' in the \'Open\' dialog box, then click \'OK.\'

3. Double click the \'HKEY_LOCAL_MACHINE\' folder.
4. Continue clicking the appropriate folder sub-directories until you find the following folder: \'HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Explorer\\User Shell Folders.\'
5. Double click \'Common Administrative Tools\' and then type in \'%ALLUSERSPROFILE%\\Start Menu\\Programs\\Administrative Tools\' in the \'Value data\' box.
6. Go to the \'File\' menu and click \'Exit\' to quit out of the Registry Editor.
7. Restart your computer to activate the changes made to your computer system.

1. Double click the file in iTunes that you're trying to play. The 'original file could not be found' error message will appear. Click the 'Locate' button.
2. Click one time on the audio or video file on your computer in the 'Locate' window now on screen. This window operates identically to any regular Windows Explorer file browsing window. Click around the directories on your hard drive until you have located the file in question.

3. Click 'Open.' iTunes will update the location of the file in its own memory to reflect its current location. The file will then play as normal in iTunes.

1. Click 'Start,' type 'Disk Cleanup' in the 'Search' box, and press 'Enter.'
2. Click the 'C' partition and press 'OK.'

3. Check the box next to the 'Memory Dump Files.'
4. Press 'OK' and click 'Delete Files.'

System Restore for Windows XP
1. Click 'Start' and then select 'Control Panel.' Next, press 'Performance and Maintenance.'
2. Select 'System Restore.'

3. Select 'Restore my computer to an earlier time' and then press 'Next.'
4. Choose a restore point from the available list. The dates of the restore points are in bold. The default selection is the date of the last 'System Checkpoint' or manual restore point.
5. Press 'Next.' When the confirmation screen appears, press 'Next' again.
6. Press 'OK' to confirm the restoration after the computer restarts and you have logged on.
System Restore for Vista
7. Click 'Start' represented by the Windows icon.
8. Go to the 'Start Search' box and type 'systempropertiesprotection'. When finished, press 'Enter.'
9. Go to the System Protection tab and press 'System Restore.'
10. Select 'Choose a different Restore Point' and then press 'Next.'
11. Select the restore point from the available list and then press 'Next.' When the confirmation screen appears, press 'Next' again.
12. Press 'OK' to confirm the restoration after the computer restarts and you have logged on.

1. Confirm that Windows XP is not running in Safe Mode, as this prevents the Windows Installer Service from operating. If you aren't sure, click the 'Start' button and then click 'Turn Off Computer.' Click the 'Restart' button and allow Windows to restart normally.
2. Press the 'Windows' and 'R' keys simultaneously. Type 'msiexec.exe /unregister' without quotation marks in the 'Run' dialog box and press 'Enter.' The mouse cursor changes to an hourglass. After a moment, full control of the computer returns.

3. Open the 'Run' dialog box again. Type 'msiexec /regserver' in the box and press 'Enter.' The cursor changes to an hourglass again, then changes back to normal.
4. Attempt to install the program that is not working properly again. If the program installs successfully, stop here. If it does not, continue to the next step.
5. Open the 'Run' dialog box. Type 'regedit' in the box and press 'Enter.' The registry editor appears.
6. Click the 'HKEY_CLASSES_ROOT' folder on the left side of the window.
7. Click the 'Edit' drop-down menu at the top of the window, and then click 'Permissions.'
8. Click the 'Add' button. In the text box at the bottom of the window, type the word 'SYSTEM' and click 'OK.'
9. Click the word 'System' in the 'Permissions' window. Place a check in the box labeled 'Full Control' under the 'Allow' column, and then click 'OK.'
10. Close the registry editor and restart Windows. You should now be able to install the software.

Disable System Restore
1. Click on the 'Start' button, then right-click 'My Computer.'
2. Select 'Properties.'

3. Click on the 'System Restore' tab in the 'System Properties' window.
4. Click the check box next to 'Turn off System Restore.'
5. Click 'Yes' to confirm.
Update Antivirus Software and Scan Computer
6. Update your antivirus software with the latest version by opening the software and clicking to your 'Update Manager' or to an aptly named 'Update' function.
7. Click on 'Update Now.'
8. Reboot the computer. Press the F8 key after the computer restarts but prior to the appearance of the Windows splash screen.
9. Choose to start Windows in 'Safe Mode.' Press the 'Enter' key.
10. Go to the 'Scan' function of your antivirus software. Click on 'Perform Full System Scan.'
11. Quarantine or eliminate any infected files the scanner finds.
Remove Registry Entries
12. Click on the 'Start' button, then 'Run.'
13. Type 'regedit.' Press the 'Enter' key.
14. Click on 'Edit' in the toolbar. Select 'Find.'
15. Enter each key listed in the Symantec link under 'References.' Highlight the entry, if it is not already highlighted, then right-click on the entry. Select 'Delete.'
16. Click on 'File,' then 'Exit' after you've deleted all keys.
17. Restart the computer. If the 'Critical System Error' message does not reappear, you may re-enable 'System Restore.' Follow the instructions in Section 1, and uncheck the box next to 'Turn off System Restore.'