Thanks for the many good suggestions. Alt-Ctl-Esc and Alt-Ctl-F1 do not work once the mouse has frozen. It is probably more like Xorg has frozen. The mouse has not been changed and xorg.conf looks to be correct. Legacy USB support was not enabled in the bios. It is definitely an Xwindows/Xorg problem, because nongraphical system works with no problem, even the mouse works if not running Xwindows. Gary