Perhaps it's coincidence, but in the past week or so I've suddenly found problems with the cursor freezing on my XP laptop (running AVG Free) and XP PC (running BitDefender). It just freezes completely, and you can't do anything except use keyboard shortcuts to launch Task Manager, shut everything down, and reboot (of course, not everything will shut down with just keyboard shortcuts!). I could accept a mouse failing, but for one mouse and one trackpage cursor to fail more or less simultaneously suggests there might be a software problem of sorts - an update, perhaps? - or the dreaded malware, so I wondered whether I was just a one-off, or whether there's something more widespread happening?
I'm not sure whether it's associated with any particular program running, although I did wonder at one point whether Firefox might be implicated.