I tried everything listed in this discussion - I changed the names on the 2 xlb files, checked to disable the accelerating, I rolled back my video drivers, but my problem was that when I double clicked a workbook, the workbook didn't open. Excel opened,
but not the workbook, i.e. it said "Excel" at the top, not " 'name of file' - Excel". The workbook wasn't opening, but once in Excel, I could go to FILE, OPEN, then navigate it to it and open it.
Anyway, I used the online repair option in the Programs & Features in the Control Panel and it worked. This discussion is a rat's nest.
Thank you.