Message also said, "Close the program or wait for it to complete its operation, then open Windows Live Mail again."  I disconnected from the web to avoid viruses, and then shut down Norton Anti-virus and Anti-spam."  WLM still wouldn't open.  Then I left the computer on overnight and in the morning WLM opened.

I wonder if WLM wouldn't open because it was compacting?  It is set to compact every 100 times it closes.

If that is the case, could I simply disable the compacting function, since I have plenty of hard drive (SSD) space?

If that isn't the issue, what could it be?  It has happened several times, and Windows Essentials repair doesn't help.  The only solution seems to be to wait for this "operation", whatever it is, to finish.

Thanks in advance.