Something to try...

Format | Cells | Number (tab) | Custom (in the drop down)
In the right-hand drop down, custom number formats are displayed at the bottom.
If the "Delete" button is enabled then the format is custom.
Delete any that you do not use - only one at a time can be deleted.

That may loosen things up a little.
--
Jim Cone
San Francisco, USA
http://www.realezsites.com/bus/primitivesoftware
(Excel Add-ins / Excel Programming)



"Leslie D"
wrote in message
One of our users is getting the above error message everytime she opens Excel
2000. She does work quite often on a document that has custom number
formats, however, this message is coming up when opening Excel versus opening
the document itself. We've tried to repair Excel, but it doesn't fix it.
Any help would be appreciated. Thanks.