Since switching from Windows XP with OUTLOOK email to Windows 7 with Windows Live Mail under Windows Live Essentials 2011, I to have experienced this error message and lock up problem.  My wife and I have two separate profiles and two separate email accounts all coming from the same POP server.  Both of us have experienced this problem in our email, me twice, her once so far.  working with Dell support on our new computer, we finally determined that the problems were caused by corrupted emails. Once in the outbox, and another in the inbox.  We were unable to open, respond to, or delete emails once the account locked up.  I was able to clear the problem once by selecting every email that had the error message at the same time and deleting all at once.  The other time, Dell was able to finally solve the lockup but I can't tell you exactly how they did it. 

 I'm concerned that this problem has occurred three times.  Additionally, since switching to Windows Live Mail I continually get duplicate emails about 90 percent of the time from random senders.  My wife has experienced this problem once or twice also.  I'm trying to solve both these problems with this new mail setup.

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