1. Run System Restore to revert your computer to a previous configuration if Windows begins displaying a Blue Screen of Death after you install a new device driver or program. Open the Start menu, type 'System Restore' in the 'Search programs and files' field at the bottom and click the 'System Restore' icon when it appears on the results list. If the change you made to your computer prevents it from starting normally, restart the computer and tap the 'F8' key before Windows loads. Highlight 'Save Mode' and press 'Enter' to start Windows in Safe Mode, which skips loading non-essential device drivers and startup programs.
2. Check your computer for a cooling issue that causes the processor to overheat. If your computer's fan always spins at the maximum possible speed -- or never spins at all -- it is possible that the air vents are blocked or that the fan has stopped functioning. Resolving a cooling issue often requires opening the computer, so hire a professional for help if needed.

3. Check your computer for viruses. A virus infection often makes a computer behave in unpredictable ways, possibly resulting in crashes. If your computer has no anti-virus software installed, install a free program such as Microsoft Security Essentials, Avast! or AVG. Run a full scan of all files on the computer to locate and remove a virus infection.
4. Remove any hardware that you recently installed if you began to see a Blue Screen of Death after installing it. Bad memory -- though rare -- can cause this type of error message. You may also see blue screen errors if the power demands of new hardware exceed the specifications of the computer's power supply. If you installed a video card that requires an auxiliary power connection, you may also need to upgrade your computer's power supply.
5. Scan your hard drive for errors. Windows has a built-in tool for this; open the Start menu, click 'Computer,' right-click the icon for your computer's primary hard drive and select 'Properties.' Select the 'Tools' tab and then click the 'Check Now' button under the 'Error-checking' header near the top of the window. Many hard drive manufacturers also distribute tools to diagnose hard drive issues. Check the support website for the hard drive manufacturer for a 'Downloads' section to see if a tool is available for your hard drive.