Yeah i think that was the problem indeed. It boots again

Now i have a other problem, it seems that the machine gets a lot slower when playing HD movies, with 10.6.3 everything was fine. Did the drivers change? Anyone else with the same problem?
Edit:
Found this...
"It appears to be 'only' happening on Macs with an nvidia graphics card or chipset, and is an apparent problem with certain OpenGL routines (not all) and the NV50HAL Graphics Driver that ships with 10.6.4
It also render CUDA (3.0.14) unusable).
nvidia are aware of the problem, and there is a bug report with Apple.
What they are doing, and time frame is a question only they can answer... "