Blue Screen of Death (BSOD), also called a STOP error, is an error screen displayed after a fatal system error. A Blue Screen of Death is usually hardware or driver related. Most BSODs show a STOP code that can be used to help figure out the root cause of the BSOD. How to fix it: The most important BSOD troubleshooting step you can take is to ask yourself what you just did. Did you just install a new program or a piece of hardware, update a driver, install an update, etc.? If so, there's a very good chance that the change you made caused the BSOD. Undo the change you made and test again for the STOP Error. Depending on what change you made, some solutions might include: (1) start up using Last Known Good Configuration to undo recent registry and driver changes, (2) use System Restore to undo recent system changes, and (3) roll Back device driver to version prior to your driver update. Verify that a minimum amount of free space is available on your Windows partition. Blue Screens of Death and other serious issues, like data corruption, can occur if there's not enough free space on your primary partition used for the Windows operating system. Scan your computer for viruses. Some viruses can cause a Blue Screen of Death, especially ones that infect the master boot record (MBR) or boot sector. Apply all available Windows service packs and other updates. Microsoft regularly releases patches and service packs for their operating systems that may contain fixes for the cause of your BSOD. Update drivers for your hardware. Most Blue Screens of Death are hardware or driver related so updated drivers could fix the cause of the STOP error. Check the System and Application logs in Event Viewer (7/Vista | XP) for errors or warnings that might provide more clues on the cause of the BSOD. Return hardware settings to default in Device Manager. Unless you have a specific reason to do so, the system resources that an individual piece of hardware is configured to use in Device Manager should be set to default. Non-default hardware settings have been known to cause a Blue Screen of Death. Return BIOS settings to their default levels. An overclocked or misconfigured BIOS can cause all sorts of random issues, including BSODs. Make sure all internal cables, cards, and other components are installed and seated properly. Hardware that's not firmly in place can cause a Blue Screen of Death so try reseating the following and then test for the STOP message again: (1) reseat all internal data and power cables, (2) reseat the memory modules. and (3) reseat any expansion cards. Perform diagnostic tests on all hardware you're able to test. It's highly likely that the root cause of any given Blue Screen of Death is a failing piece of hardware: (1) test your system memory, and (2) test your hard disk drive. Update your BIOS. In some situations, and outdated BIOS could cause a Blue Screen of Death due to certain incompatibilities. Start your PC with essential hardware only. A useful troubleshooting step in many situations, including BSOD issues, is to start your computer with the minimum hardware necessary to run the operating system. If your computer starts successfully it proves that one of the removed hardware devices was the cause of the STOP message.