Never heard of this issue before, but I've had windows 7 64-bit for over a year and I've been using mousekeys for well over a year too, no problems whatsoever. Do you think you can give more detail to the problem? A variety of mousekeys problems that some of my friends have had are caused by having the mousekeys icon displayed on the notificaton area on their taskbar, i don't know why this causes a problem, but when they chose the option to hide it, problems such as the display going blank after using it for too long no longer occurs. Another cause of the problem might be display aero effects on windows, are these turned on? Having them turned off has an effect on mousekeys and their jump is made shorter than usual. Its best to keep it on. I don't know if i've helped much but thats all i can input or now.