The strangest thing happened on a spreadsheet today I have been working with
for months.

I created a very simple formula in a new cell, just finding a difference
between 2 other cells: Ex: A1: 100, A2: 50, A3: =A1-A2

When moving off cell A3, it turned to zero. I double clicked it and it went
to 50. I copied the cell with a drag to the adjacent cells, and those also
went to zero (they do reference other cells with actual numbers in them).
After playing with it for a while, I got half the cells to work while the
other half show zero.

Here's the really odd thing, I started hitting F9 and found that the correct
and incorrect cells would reverse each time. The autocalc option is set to
'on', I've tried exiting and coming back in, rebooting the computer...
everything.

Anyone know what's going on?