What view are you in? Page Layout can cause this snag. Try Normal View.
If it says EXT or Extend Selection in the bottom left corner of Excel, then it is in Extended mode - try tapping the F8 key once.
The other snag may be your mouse. Is it a wireless one? The mouse may be mis-reading the cell's co-ordinates. (Is it a Logitech?)
You might also try moving the mouse up a row whilst holding down the left button. That may deselect and give you the selection you want.
Let us know!
Last edited by Spurlash2; 6th Sep 2011 at 23:43.
Reason: Amended