This morning I upgraded to ArcGIS 10.2 and after the setup I had to open an Excel file from a colleague. I was trying to get rid of some extra row and columns and as soon as I would right-click in the spreadsheet the program would crash. If I left-clicked the column letter or row number I could delete using the Cell functions on the Home tab. The original spreadsheet was saved as xls so I did a Save As to xlsx and tried the same right-clicking routines and got the same crash each time. I probably tried a dozen variations in the troubleshooting process.
On a hunch, I signed in to ArcGIS on the Esri Maps tab and tried right-clicking. It worked fine. I signed out and right-clicking still worked even after closing the document and coming back in. I can no longer duplicate the error.
I'm not saying there is a connection to the two, but the coincidence couldn't be ignored.