We have an old spreadsheet that was originally created by Excel 2000.
It is a complex workbook with many formulas.  It does not have locked
cells, nor is it protected.

The problem, is that a bunch of cells will not allow for formatting.
We can't figure out why.  If one right clicks while on the cell, the
short-cut menu appears, but if you click on "Format Cells" nothing
happens (it doesn't take you to the next menu).  The same happens if
you go through the toolbar and try to click FORMAT then CELLS.

I've searched a couple of databases and I can't find any reference to
this type of problem.  I'm hoping someone here might be able to help.

Thanks!