I am a long time user of Excel 2010 and it has, until just a few days ago, always worked perfectly. However, starting a few days ago, if I double-click a .xlsx or .xlsm file, I get the error message: There was a problem sending the command to the program. However, if I open Excel, I can then drag the file into Excel without issue.


What the heck happened? More importantly, can you suggest that which I can do to fix this problem?


Thanks.