Driver win32k.sys marked pagable instead of nonpagable

A friend has the following BSOD on Vista, about each 45 minutes:

A problem has been detected and Windows has been shut down to prevent damage to your computer.

win32k.sys

The driver mistakenly marked a part of it's image pagable instead of nonpagable.

[...]

Technical information:

*** STOP: 0x000000D3 [...]

win32k.sys

It has been that way for a few weeks, and there was no change or new install, except for a Windows Update. Moreover, he has reinstalled Windows a few weeks ago.

What is the cause/solution to that symptom?