Thanks Curio, I regained control of the mouse by a similar move, closing the document using the keyboard, and then re-opening, but I'm not looking for a short term answer, I'm looking for the basic reason why the anomaly happened in the first place and a long term cure. It would be very inconvenient to have to shut down and re-boot every time the mouse got a will of its own, and I need to know whether it's possibly a result of getting a virus or something. I'm hoping for an authoritative answer to cure the problem once and for all.
An amazing number of Word related annoyances can be eliminated by >
Use Find (Win98) Files and Folders. Then type in to the window - Normal.dot
When you are sure you have found it, right click on it and choose Delete.
Load Word again, and you should find no trace of the previous problem.
Normal.dot is part of Winword.exe and can become corrupt. This procedure makes and stores a new Normal.dot as part of the opening process. The only downside is the loss of any special changes to the Normal template which you might have made in the past
Thanks Diemmess, I've just done that, but as you well know with all these unexplained Windows anomalies, you can't tell whether you've cured it or not even if it doesn't crop up again immediately. Here's hoping.