I recently changed ISPs.  The old ISP used POP for incoming email, and the new ISP uses IMAP.  This morning I noticed that there were several emails in the ISP's web interface inbox which were not in the inbox in Windows Live Mail, but there were subsequent emails, so synchronizing did not just quit.  I called Support for the ISP, and they pointed to Windows Live Mail.  I see no errors in Event Viewer, and Windows Live Mail does not pop up any errors.

Where do I go from here?