Right?
New (to me) desktop computer, running Windows 7. When I first got it, I installed me Office 2003 Professional suite, and it was working fine.
I recently installed Office 2016 Professional Plus, in order to have file (and menu) compatibility with what we're using at work. And then, to help me adapt to the new "ribbon" menu system, I installed an add-on called UBitMenu, that allows an overlay of the traditional menu structure in Word, Excel, and Powerpoint. UBitMenu is working fine in Office 2016 -- but it somehow seems to have also tried to attach itself to Office 2003, because now when I start up Excel 2003 I get an error message telling me Excel doesn't recognize the file format.
I'm thinking of just uninstalling Office 2003, and then reinstalling it. Does that sound like a viable strategy?