We've had this happen on several diff computers. The extend selection gets turned on, from what I've been able to determine they do not press the F8. They are simply entering data and then use the mouse to select a different cell but it's anchored to the cell they were editing. Where ever they move the mouse (up, down, right or left) it mearly selects cells, the menu items and toolbar buttons can cannot be selected/clicked. Pressing F8, Esc, Scroll lock don't clear the anchor. I've had to end task on Excel (loosing data), delete the excell11.xlb file (this I discovered through trial and error) and reboot the computer in order to clear the anchor. Why the toolbar file should be effecting this I don't know. But without deleting that file it doesn't clear. We have one person this happens to quite frequently any ideas would be helpful