1. Read the screen. Te blue screen itself will provide you with a few options. It's best to try them in order of least dramatic to the most dramatic.
2. Select the option to boot Windows normally. It's possible that the computer had a simple glitch that already has resolved itself. If so, the computer will boot normally. Often, by default, the computer selects this option. Just press the 'Enter' key on your keyboard.

3. Boot into the last known good configuration. This is generally the option listed above the first one that you selected. You will need to use your keyboard arrows to highlight it. Press 'Enter' on your keyboard and see if the system boots normally.
4. Choose your final easy option. This option boots into safe mode. Highlight it, using the arrow keys and press the 'Enter' key. If you are successful, you will be in safe mode. The safe mode is a troubleshooting aspect of Windows in which most of the advanced functions are disabled. At this point, you will want to shut down Windows normally and attempt to reboot normally.
5. Repair the operating system. Insert your operating system installation disc into your optical drive. Restart the system, and press a key on your keyboard when the computer gives you the message 'Press any key to boot from CD.' This will prompt the computer to attempt to boot from the disc in your optical drive. You will receive the option of 'Repair' or 'Reinstall.' Choose 'Repair' first because that will attempt to save all of your programs, files and settings.
6. Reinstall your operating system if none of the other options work. This will restore your computer to its original factory settings. Insert the operating systems installation disc into the optical drive, restart the system and press a key when prompted to boot from CD. From the options you receive, choose 'Reinstall' and click 'OK.' The computer will automatically reinstall the software.