Checking the # of hard faults is a good idea. Without some more digging it is hard to say what the cause could be. When the problem occurs, it would help if you took a snip of task manager (the lower part with the numbers) and posted that here.
I would also suggest you check with Process Explorer ( Process Explorer
) which processes bring your system to a creep. Click on "CPU" so that all the CPU eaters appear on top. Then right click on the processes that consume the CPU and go to Properties. That will give you further detail. If it is a svchost.exe, hovering over the process already gives you some more info.