I have a spreadsheet with a couple of Worksheet__Deactivate macros that put up a message box and do some other tasks. They work fine on my machine (Excel 2003) but don't appear to get called on a colleagues (Excel 2000) - at least the message boxes don't appear.

I am at a loss to explain the difference and as the other person is not VBA literate and at the other end of a phone it's hard to find out more. I got him to open the VBA editor and manually execute the macro, and that works. His security settting is Medium and to date all the other macros in the spreadsheet work.

Does anyone have any ideas why the deactivate macro isn't being called and what I might look for to troubleshoot?

Thanks.