At first I thought it may be a mouse problem; but today, with two different
worksheet open side-by-side, this would happen in one worksheet but not the
other. I try to pick just one cell, but the cell I pick plus the four or
five cells below it get highlighted. It makes copying & pasting all but
impossible. The problem is intermittent too, it starts and stops with
seemingly no reason. Has anyone else experienced this?

Excel 2007, Win XP SP2