Mymachine runs fine most of the time.

However, at times it runs extremely slowly so that the mouse judders ans and sounds are broken.

Task manger shows 40-50% CPU usage but nothing in the proceses is using that (I have all user thing ticked).

I wonder if this is an over-heating problem as I once saw a fleeting boot-up message about a "previous fan error". I can hear a fan though! The room is cool.

So, would over-heating cause this? If so how can I tell if it is in fact this?

Cheers!

Over heating could cause your computer to slow down. I don't know that it would cause it to use compute cycles. Everest can tell your motherboard temps. (http://www.majorgeeks.com/download4181.html)

Thanks Cinders.

Everest only shows the GPU temperature.

I guess this means that the motherboard/CPU don't have one?

Umm you should have a CPU temp. Maybe you're just not looking in the correct place, or Everest missed your CPU temp, so look and try again.

Thanks mate but no, it doesn't want to know. I bet there is no sensor on the thing!