Toshiba Tecra & Excel cells

Have several Toshiba Tecra V2’s. Cells get highlighted while moving the mouse across the screen. We usually have to reboot when this happens; this is the chain of events, hit escape, click the mouse off or even kill Excel, nothing works. Got the latest Office Patch, Windows.. Toshiba wasn’t much help blaming office but these machines are the only ones with this issue. Any ideas?