"Insert row" hiding/blanking other cells

[jammin7800]

MS Excel 2007. Very strange behavior. I insert a row at Row 662. When I do that, certain cells below it become blanked (or hidden). That is, UNTIL I click, hold, and drag my cursor over those cells. Then the hidden numbers magically re-appear.

Why is this happeneing and how do I stop it? I thought it was deleting my numbers at first. It's a little un-nerving.

 

[jammin7800]

Now its getting worse.

 

[jammin7800]

Now the blank/hidden cells are popping up all over the place. It's as if someone randomly used invisible ink on the cells.