I'd try reconstructing the calculation dependency tree; press
CTRL+ALT+SHIFT+F9.
Note that Excel has one setting for automatic or manual calculation for all
workbooks open in that instance of Excel. The first workbook opened
determines the setting.

--
Kind regards,

Niek Otten
Microsoft MVP - Excel


"amted88" wrote in message
...
We have McAfee running constantly. Would uninstalling and re-intalling
Excel
help? what do you think?

"MimiS" wrote:

Could be a virus on your computer or in the Excel files.

"amted88" wrote:

I have Office 2003, this started a couple of weeks ago that simple
formuls
like Sum or =A1+A2, etc, will not calculate. These are worksheets that
work
when I have them open and then a little while later will not work when
I open
them again. I can close and not save and then try to open them again
and the
formulas will work the next time (sometimes I have to open and close it
4 or
5 times before it works).

It seems to be happening more frequently now.

I checked that autocalculate is checked. Even hitting F9 will not
work.