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Was this re-image of the old drive (old settings etc) or a new install of Vista?
We've seen a few threads here recently that people are having problems with their system process which we think we narrowed it down to the power management driver running amoc, although this isn't verified for vista yet.
If you have any hardware information, that would be most helpful. Cpu, amount of memory, graphics card and how big your power supply you have. If this is a laptop, just shoot us the make and model.
That it runs in ntoskrl.exe could mean that it is a driver that is not running like it should.