It has been ages and I don't have this combo or problem any more, but I may have stumbled across some info and solution. Looking through the release notes of the 91.45 drivers I found this:
AGP and PCI-E Programs May Hang With AMD K7 and
Microsoft® Windows® 2000 and Windows XP systems using AMD K7 and
K8 processors can hang when an AGP or PCI-E program is used.
• Root Cause
There is a known problem with Microsoft® Windows® 2000 and Windows
XP systems using AMD K7 and K8 CPUs that results in the Microsoft
operating system allocating overlapping 4M cached pages with 4k writecombined
pages. This condition results in undefined behavior and data
corruption, and is explicitly disallowed by the AMD CPU manual.
This problem can affect any device driver in the system that allocates writecombined
system memory, but is usually most easily reproduced with
graphics drivers since graphics drivers generally make heavy use of writecombined
system memory for performance reasons.
Microsoft has a knowledge base article on the issue, the text of which is
unfortunately quite outdated. While the article only mentions Windows
2000, AGP, and K7, both the root cause and resolution also apply to
Windows 2000 or WindowsXP, AGP or PCI-E, and AMD K7 or K8. The
article can be found at http://support.microsoft.com/?id=270715
The issue is resolved by applying an operating system registry key as
described in the referenced article that instructs the Microsoft operating
system to not use the 4M pages, thus avoiding the conflict.
The registry key is automatically applied by installation of the latest NVIDIA
nForce platform driver package (including 4.57 SMBUS or later). It is
imperative for the package to be installed or for the registry key to be applied
before the NVIDIA graphics driver or any other device drivers are installed.
The registry key takes effect only after an operating system reboot.
I think it is worth a try to all of you still experiencing this combo and problem!!