Hmm...
Has it just recently started? If so, anything installed or removed around
then?
Is it really taking you to the Outbox, or the Inbox?
Is there anything in the Outbox?
Does it happen with every email you get?
Try going to Tools->Options->Email Options->Advanced Email Options and
uncheck everything under "When new items arrive in my Inbox" and then try
sending yourself an email. If that works then start checking things back off
and testing it.