x61 with high cpu load when not doing anything

Hello!

I have cpu issues with my x61 with Vista Enterprise (look below for system details). The cpu load is very often between 50-70% when I'm not doing anything. It's the System - NT Kernel & System process that's taking up the load. It's not only eating my battery and working slow, this also prevents me from using the sleep and hibernation functions in Vista. It won't sleep/hibernate if the load is over 50-60%. The screen goes black and after a while the laptop restarts. After log on Vista tells me the system wasn't shut down properly and tries to find a solution, but can't find anything. If the load is below 50% I'm able to sleep/hibernate. I've used WinDebugger on "memory.dmp". It says that "ntkrpamp.exe" probably caused the problem. I suspect it has something to do with the graphics driver. When the load is 50-70% the harddisk isn't active, so I don't think it has something to do with indexing.

Anybody having the same problem, or better; anybody having a solution?

Summary:
- X61 with Vista Enterprise
- Cpu load 50-70%
- System - NT Kernel & System
- Eating battery
- Won't sleep/hibernate
- Probably ntkrpamp.exe
- Graphics driver?

This is my system:
- Intel Core2Duo T7300 2.0 GHz
- 2 Gb Ram
- Mobile Intel 965 Express Chipset Family
- Vista Enterprise edition with all updates