Starting game error (1 Viewer)

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2009.12.21 16:59:31
OS : Windows Vista 6.1 (Build: 7600)
CPU : GenuineIntel  Intel(R) Core(TM)2 Duo CPU    E4600  @ 2.40GHz @ 2409 MHz 2047MB RAM
Video : NVIDIA GeForce 8600 GTS (9038)
PosCode : LS8(83) 0:0:0 2/0 [428]
IDirect3DIndexBuffer9::Lock failed(80070057).
History: FD3DDynamicIndexBuffer::AddIndices [- FD3DRenderInterface::SetDynamicIndexBuffer [- FBspDrawList::Render [- Material=L2_Skies.Shaders.SkybackgroundColor [- SolidRendering [- RenderLevel [- FLevelSceneNode::Render [- FSkySceneNode::Render [- NoStencilRendering [- RenderLevel [- FLevelSceneNode::Render [- FPlayerSceneNode::Render [- ViewportLock1 [- Precaching [- UGameEngine:raw [- UWindowsViewport::Repaint [- UWindowsClient::Tick [- ClientTick [- UGameEngine::Tick [- UpdateWorld [- MainLoop

I have this with the nvidia 1.90 drivers on Win7. All other games work fine (that i have on pc). Any ideea how i can fix this WITHOUT changing the driver?
I ask this because older drivers don't even install and newer ones give me all kinds of problems. With the 191 driver i get, i don't even know how to explain it, textures keep poping in/out (dissapearing / appearing) and the game freezes when this happens then unfreazes when they appear again. And with the 195 drivers i get really really poor performance in loading times. It's like i got 512 ram or less.
P.S. With 191 i used to fix that problem by restarting the pc. It happened once a week or even less. But since this morning the restarting didn't fix the problem so i had to try other drivers. None were good though :'((