>Now I've had a bit of strangeness recently myself. My entire system (dual processor, mirrored RAID C: drive) simply stops 'accepting' mouse clicks for periods up to 30 seconds@#!$@#@#!$@

Check Task Manager for a running InternetExplorer (iexplore.exe) sucking up 100% CPU. I've found that even when there's no other IE windows open. I wonder what the hell it's trying to do without being seen?

[Update]
Also, another thing I've encountered that mysteriously slows things to a crawl every 30 seconds or so:

Once Windows has performed it's regular updates, sometimes, after the first re-boot after the update, it goes into that 30 second crawl. Re-booting a second time seems to cure that problem.