What are some common causes of BSOD?

[color blue]DIVIDE_BY_ZERO_ERROR[/color]
[tab]This error is caused by an application trying to divide by zero. If you receive this error and donÆt know which application caused it, you might try examining the memory dump.
[color blue]IRQL_NOT_LESS_OR_EQUAL[/color]
[tab]The IRQL_NOT_LESS_OR_EQUAL error is caused by a buggy device driver or an actual hardware conflict. If youÆve recently added new hardware to your system, try removing it and see if the error goes away. Likewise, if youÆve recently loaded a new device driver, you might try using ERD Commander Professional Edition, by Winternals Software, to temporarily disable the new driver and see if the problem goes away.
[color blue]KMODE_EXCEPTION_NOT_HANDLED[/color]
[tab]An incorrectly configured device driver usually causes this type of error. You can use another section of the blue screen to figure out which driver is causing the problem.
[color blue]REGISTRY_ERROR[/color]
[tab]Such an error indicates a catastrophic failure in the systemÆs registry. However, this error can sometimes be caused by failure to read the registry from the hard disk rather than because the registry itself is corrupt. Most of the time though, if you get this error, youÆll have to restore from backup.
[color blue]INACCESSIBLE_BOOT_DEVICE[/color]
[tab]Just as the name implies, this error indicates that Windows NT is having trouble reading from the hard disk. This error can be caused by a faulty device driver or a bad small computer systems interface (SCSI) terminator. If youÆve checked for these problems, but are still receiving the error, check to make sure that a virus hasnÆt destroyed your boot sector.
[color blue]UNEXPECTED_KERNEL_MODE_TRAP[/color]
[tab]This error message is almost always caused by your computerÆs memory. If you receive this error, check to make sure that all of your single inline memory modules (SIMMs) are the same type and speed. You should also check to make sure that your computerÆs Complementary Metal Oxide Semiconductor (CMOS) is set for the correct amount of RAM. If all of these suggestions check out, try replacing the memory in the computer.
[color blue]BAD_POOL_HEADER[/color]
[tab]This is, perhaps, the most obscure error message. In most cases, if you receive this error, itÆs related to the most recent change youÆve made on your system. Try undoing the change to get rid of the error.
[color blue]NTFS_FILE_SYSTEM[/color]
[tab]An NTFS_FILE_SYSTEM error indicates hard disk corruption. If your system is bootable, run CHKDSK /F on all of your partitions immediately. If your system isnÆt bootable, try installing a new copy of Windows NT in a different directory. You can use that copy to run the CHKDSK program. When youÆre done with the second copy, you can edit your BOOT.INI file to make your computer start your original copy of Windows NT.
[color blue]KERNEL_DATA_INPAGE_ERROR[/color]
[tab]This error indicates that Windows NT wasnÆt able to read a page of kernel data from the page file. Bad memory, a bad processor, incorrectly terminated SCSI devices, or a corrupt PAGEFILE.SYS file may cause this situation. The first step in correcting such an error is to recreate the PAGEFILE.SYS file and see if you can bring your system back online.
[color blue]NMI_HARDWARE_FAILURE[/color]
This is a generic error message in which the hardware abstraction layer canÆt report on the true cause of the error. In such a situation, Microsoft recommends calling the hardware vendor. This error can sometimes be caused by mixing parity and non-parity SIMMs, or by bad SIMMs.

Thanks to MASTERRACKER for supplying this information