This happened to me too. But I believe it is related to my ISP server
crashing, while Outlook automatically sends/receives mail into my
Outbox/Inbox. I think Outlook is confused and trying to find the *.pst file
it uses to dump incoming/outgoing mail. My mistake was that I didnot ARCHIVE
the incoming/outgoing mail onto MY HARDDISK (hence, into my archive *.pst
file, which is fully recoverable). When my ISP server crashed, Outlook froze
and hence locked up the active *.pst it uses to dump the incoming/outgoing
mail (probably because it is still in my ISP's server "purgatory"). I was
warned by my ISP that I should regularly and frequently ARCHIVE my
incoming/outgoing mail to avoid losing recent stuff, even CONTACTS (EXPORT to
Excel). *sigh* So, first, I had reset my Profile email accounts under the
"Mail" application in Windows Control Panel, and had all of them point to a
different *.pst filename for incoming/outgoing email. Then, I ran
scanpst.exe on all my *.pst files, and I successfully repaired them if they
had errors (which they did!). Then I was able to start Outlook, noticing
that a new set of folders called "Recovered Personal Folders" appeared, and
also my original "Personal Folders" appeared - maybe from repairing the *.pst
files with scanpst.exe? (Ok, I'm kind of a lay person, can't you tell?!).
Anyways, I immediatelly archived everything which is now on my HD, even
exporting the contacts to the excel file. Tomorrow, I'll back up my HD ...
hopefully that won't crash either!