Mouser,
I've now uninstalled and re-booted the PC.
It's been running for about 20 minutes with no slow-downs or 100% CPU use.
So I guess it was something to do with NOD32.
Thanks,
Nick

Mouser,
Thanks for the reply.
I have already been thinking that NOD32 is the culprit as this is a recent phenomenon which coincided with the installation of NOD32!
I haven't got time to try working out which driver may be causing the problem so I think I might completely uninstall NOD32 and see if that improves things.
And maybe I should drop them a line to see if they can offer any advice.
Thanks,
Nick

HELP!
I've just downloaded Process Tamer in the hope that it might help to tame or explain the high CPU use of the system process on my system - it should run at about 0 or 1 percent but it's regularly (every few minutes) running up to +90% ... which is ridiculous and causes constant system slowdowns.
Note: I'm not referring to the system idle process - this is a separate process which has the name system and which is detailed on various websites as a virus-free Windows counter process.
Rather oddly, Process Tamer doesn't even show the system process but WinTask 5 and the old faithful Windows Task Manager do.
Constantly worrying about viruses, trojans, etc, I've run various versions of the latest virus checkers (Norton, AVG, NOD32, etc) but they all report no viruses, trojans, etc.
Can anybody help?
Thanks,
Nick