9700 Pro and certain racing games stopped working

Hi guys, hope some one can shed some light on a little problem I've
developed. Done some searching around but can't find anything about this
particular problem.

Firstly, the setup
Abit NF7S-V2.0 mobo
XP3200+ CPU
1GB Crucial PC3200
Radeon 9700 Pro
3x160GB Hard drives 1xIDE 2xSATA

Up until a few days ago everything as running smooth as silk. No issues
at all, I then decide to play a couple of games I've not played in a
while. Need For Speed Underground 2 and Toca Race Driver 2. Neither
games are playable anymore. Front ends load fine, but when you get into
a race, FPS have dropped to 0. It's unplayable, the countdown from 3 to
start a race can take 20-30 seconds. This doesn't happen in any other
game, I've checked other racing games (Colin McRae 2004) and that works
fine.

All drivers are up to date, I've unistalled drivers and tried vid
drivers 4.10 thru 5.2, each time clearing out the old ones thoroughly
first. I've updated and checked DX, it's already got 9.0c installed, run
through dxdiag with no problems found.

I've unistalled games, installed to new locations, made sure they're
updated with latest patches. Nothing works.

Every other game I play works flawlessly, I've made no hardware changes
or additions to the base unit in months, apart from adding a 19" LCD
monitor to replace my old 19" CRT one. But that shouldn't cause any
issues. It's a fast response monitor 16ms, and like I say everything
else works flawlessly. No problems with the games I play most, BF1942,
BFV, HL2, Doom 3, The Sims 2.

I just can't find any reason for this happening, I've tried everything I
can think of. Made every possible change in the vid card settings,
turned off all AA and AF.

Has anyone else come across the same problem?

Cheers
H