piskie - 2:16 pm on Jan 21, 2008 (gmt 0)

Thanks for the suggestions Kaled.

After exploring every thing (and more) I have now had 24 hours without the symptoms returning. The fix (or fudge) was to remove the USB Mouse plus software and reintroduce it via a PS2 adaptor. No further Bloops since. No reasonable clue as to why though.