Wrong function entered from menu

[nnklem]

I have a minor, but infuriating issue that I hope the community can assist me with. Sometimes, 60-70%, when I choose a function from the ribbon menu in Excel 2010, it enters a completely different function into the spreadsheet than what I chose. For example, I will choose VLOOKUP and it enters a VDB function or sometimes a WEEKDAY function. Most times, I just delete and choose again and it enters the correct function. Any idea how I can fix this?

 

[Zot]

The only thing I can think of right now is to re-install MS Office