internal driver error

When i run HL2.exe (Counter Strike:Source or DoD:S) the game crashes just before the map loads. The error message pops up "Engine Error
internal driver error in IDirect3dDevice 9:resent()". This problem only effects hl2.exe and not other games (eg oblivion) which makes me wonder whether it is an error in the driver. I followed the advice in the thread http://forums.majorgeeks.com/showthread.php?t=110312&highlight=idirect
But it hasn't helped. Also this message is only present half the time, other times hl2 works perfectly.

My System:
3.2 GHz intel pentium 4 with HyperThreading
XP with SP2
Vid Card: RADEON X700 pro (256mb DDR3)
DirectX Driver Name: ati2dvag.dll
RAM: 1023 Mb (DDR2)
Gigabyte GA-8I915PDG s775 motherboard

If any1 can help i would really appreciate it.

Thx