Cannot open your default e-mail folders

All of a sudden, my Outlook 2007 stopped to update mailbox even though it was connected to the Exchange server. I then created a new Outlook profile, but got 'Cannot open your default e-mail folders'. Found the solution here, http://support.microsoft.com/kb/913843.

What I did is to manually create the RPC key and the dword key. Then my Outlook opened right away and started updating items.

Updated 8/7/13
This issue reoccurred again today. Checked the registry and it's good. The workaround this time was to go to email account, and remove username and re-type in, click "Check Name" again.

Updated on 9/15/14
This issue occurred on one of user's PC. He has Outlook 2007 connecting to Exchange 2003. The Outlook status was "disconnected' and no matter what I tried, even tried on a different PC, did not resolve the issues. I finally found out it's MAPI related and limitation on Exchange 2003. This article below helped me resolved the issue. http://support.microsoft.com/kb/842022