Stumped on this one.
A colleague was using one of our common spreadsheets, doing some copy/pasting from another similar sheet when he called me over.
His formulas were converting themselves to numbers.
I saved the sheet on our network drive (the usual location) and took a look.
If I, for example, go to cell H8 and enter "=SUM(H9:H24)" as soon as I hit enter I see the answer ($10,000). But there is no longer a formula in H8. It's a value: $10,000.
Doesn't matter which cell I put the SUM into.
Doesn't matter if I make a more complex argument, i.e. IF(....)
As soon as I hit enter, the cell converts to the answer of the formula, and the formula is gone.
Likewise, if I hit F2 and ENTER on any of the pre-existing formulas on the sheet, they convert to the answer.