Windows not shutting down/CPU 100% constantly

Hello, I hope this is the right forum for this....

My computer has been screwing up recently, with the CPU usage constantly at 100%. The culprit process claims to be 'System', which is now using about 96%. Additionally (and I do not know if this is connected at all), my computer refuses to shutdown or restart. It hangs when it get to the Windows 'Your computer is shutting down' screen.

I have read lots of forums, and treid many things. I have:
*installed and run Notron Antivirus after doing a 'Live Update' (nothing bad found)
*run SpyBot Search and Destroy (a couple of Ad ware things found)
*run BlasterFix (just in case...!)
*started the computer in Safe Mode (CPU still at 100%)

Still the CPU remains at 100%. So, I got really annoyed with it, so I backed up all my work, and did a System Restore from the CDs that I got with the PC when I bought it. Everything seemed to run during that, except at the end when it trys to restart, it hung (hanged?!?). And STILL my CPU is up at 100%!!!

Now, from my understanding, the System Restore was going to put the settings, files, etc back to how it was when I bought it... in that it didn't fix my problem, could it be that this is a hardware issue rather than corrupted files or virus issue?

Any help on this would be very gratefully appreciated.... Many thanks.

 

Plus have you check your msconfig? You may have too many processes starting up.

 

Hey,
No, I do not have a Nvidia GFX card, and do not do any sort of online gaming stuff, so nothing that *should* be zapping the juice!
I *did* have NT home running, SP1, with lots of hotfixes on it. I have now tried to bring it rightback to where it started by reinstalling SP1. I've also got the SP2 CD to install that, but neither thing helped!!!

I have used MSConfig to start the compter up in 'Diagnostic' mode, but again, same thing happened. (doesn't shutdown properly, CPU 100%). I will have another look this evening to see if there are too many processes starting up which I can manually kill before they get going!...
Thanks for the help so far, any other ideas, I'm all ears!