I am using 25Khz kernel, but have tried a few other speeds but get the same.

The old system that I have just upgraded from was also running Windows 7 Home Premium 32Bit SP1, I did not have any motor stalling problem, just that the system was very slow at booting and loading programs.

I can try installing windows xp on a spare hard drive if I can find my old windows xp install cd.

I don't think this problem is a OS / Software related problem, I think it's a hardware issue with the motherboard it's self.

But anything is worth a try.

Best Regards.