1. Restart your computer and then press 'F8' when the message prompt, 'Please select which operating system to start' is displayed.
2. Press the down arrow key and choose 'Last Known Good Configuration (your most recent settings that worked option and then press 'Enter.' (Note: Users of Windows 7 and Windows Vista, use the displayed 'Advanced Boot Options' screen.)

3. Go to Microsoft's 'Windows Updates' website to get the latest updates for your computer.
4. Uninstall or rollback the driver of incompatible hardware and software if system errors continue to present a problem.