Excel encountering erros and closing/reopening repeatedly

I've used excel for years but in the last couple months (no new upgrades to OS or Office products recently) I've started getting the message "Excel has encountered an error and must shut down" then Excel automatically re-opens and pulls up the documents I was working on (usually with all the information). I wouldn't mind so much if it just happened occasionally, but it seems to be happening 8-10 times a day or more.

I uninstalled and re-installed the software, but that did not fix the problem. I uninstalled, ran a chkdsk (no errors). Ran a defrag, then reinstalled (incase it was installing ontop of a bad sector on the hard drive). Still have the same problems.

The files I have open are very simple spreadsheets (sometimes I don't have any files open just the program) so I'm pretty sure its not caused by embedded code.

Anyone have any suggestions?