For the past couple of weeks, my laptop has had a strange problem where it looks like ctrl-z is pressed, so I usually lose bits of text I just typed. If I press ctrl-shit-z (redo), the text comes back, proving it's really as if ctrl-z was pressed.

It's difficult to see a pattern, I can be undo-free for hours, then get a few within minutes, sometimes 2-3 undoes at a time. Very frustrating!

Running WinXP+SP3 on Dell Latitude D820, Clamwin antivirus.

I've tried another keyboard, no difference.

Any clue on what this could be, or how I could trace this problem?

2009-09-25: Tried a few things that were listed or linked to on this page: http://www.selfishman.net/2008/06/24/problem-with-dell-inspiron-1501-keypress-every-second/ but nothing helped. Though it seems to point at a Dell laptop issue. I upgraded the BIOS and other drivers, but still got the problem.