Thank you for your help. Yes, I have updated to the latest A4Tech mouse drivers, three or four times in the last year or so. Things are no different on my new Compaq with its bundled Logitech mouse. Based on another person's response I am beginning to rule out bad hardware and mouse drivers.

I may have to live with the problem. I'll be interested to see if the problem persists when VFP 7 comes out.