It appears that if you were to hold down the shift key for an abnormal
length of time, that it locks on you. I don't know how to get it unlocked
other than rebooting the computer. I've tried Ctrl Alt Del and close down
the spreadsheet but that does no good. I can't open another Excel sheet
either. If I do, and I go to any area on the sheet, it happens again. It's
as if the shift key is held down. Then as I move the cursor in any
direction, it selects everything.

What can be done other than rebooting?