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General Protection Fault ("Blue Screen of Death")
Last updated: 4/25/03

Q.  What is a General Protection Fault (the infamous "Blue Screen of Death") and how does one troubleshoot it?

A.  A Windows General Protection Fault (GPF) produces the infamous "Blue Screen of Death" (BSOD), which is full screen with an error message,  and locks-up a computer.  Microsoft defines it as:

"General Protection Fault (Interrupt 13)

All protection violations that do not cause another exception cause a general protection exception. This includes, but is not limited to:

  • Exceeding the segment limit when using the CS, DS, ES, FS, or GS segments. This is a very common problem in programs; it is usually caused by miscalculating how much memory is required in an allocation.
  • Transferring execution to a segment that is not executable (for example, jumping to a location that contains garbage).
  • Writing to a read-only or a code segment.
  • Loading a bad value into a segment register.
  • Using a null pointer. A value of 0 is defined as a null pointer. In Protected mode, it is always invalid to use a segment register that contains 0."

When I see one of these errors and I do not know the cause, and the error message includes the name of the task/module producing the interrupt, I usually search Microsoft's Knowledge Base with the version of Windows and the error message.  If that does not produce an answer, I search Google with the error message.  If that doesn't do it, I search again with just the task/module name.  Finally, one can resort to Microsoft's troubleshooting, tips, etc. for these kinds of problems.

One thing that can cause "jumping to a location that contains garbage" is bad memory or other hardware problems such as a noisy power supply.  Whereas, Microsoft emphasizes software problems as the cause of BSOD's, I have seen a lot computers where the real cause was defective hardware or faulty/dated hardware device drivers.


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Also, see Windows Tips and Tricks.

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