Hello CGM3 (Computer Generated Man, version 3?)
Thanx for the reply. I have already tried to change the file association from Excel 2013 back to Excel 2010, but when I browse to Excel.EXE (2010) and click save, there is a video flash on the screen (like it's trying to add Excel 2010 to the list and then erases it), and only Excel 2013 is shown. To clarify, I right clicked an xlxs file, clicked "open with" and then tried to select Excel 2010. Like so many products these days, I guess Excel 2013 thinks it's the only thing suitable to use, and someone cancels the request for changing the association to an older version. Interestingly, when i try the same procedure with an XLS file, I get the same results. It seems like Microsoft has hardwired something to only allow association with the latest executable.

I suspect my only cure is to uninstall all the old stuff and reinstall 2013. I had intended to do that in the first place, thinking that when I was downloading Office 2013 I could install it later. In actuality, the file I downloaded was setting up Office 2013.

I have been wanting to purge my computer and do a clean install of everything, and I guess this is as good a reason as any.