Geforce ti4200 long pauses during MOH and Dungeon siege games, any way to fix?

Here's my system:

amd 2000+
512 mem
xp pro
asus a7n8x - deluxe mobo
pny geforce 4200 128meg 8x agp

All new drivers and bios installed
directx 9.0b

Here's the problem.
I installed the latest video drivers and then upgraded the new
directx, and now all my games pause for a couple seconds at random.
No error messages are displayed.

The system works great otherwise.

I have tried everything. Reinstalled drivers, reinstalled winxp, put
back directx 9.0a (which worked before), installed old drivers that
worked. Nothing works.

Any suggestions will be helpful.

Lee