Hi,
Which account type are you using?
Can you start Outlook in safe mode? Press Windows key + R, type outlook.exe /safe in the Run command and press Enter.
In addition, please try to run a repair of your Outlook data file to check the result:
http://support.microsoft.com/kb/272227/en-us
You may need to run Scanpst.exe for several times until there is no error in your data file.
We can also try /resetnavpane switch to check the result. Just type outlook.exe /resetnavpane in the Run box and press Enter.
If the issue persists, please create a new mail profile from Control Panel and re-setup your email account in the new profile to check the result. See:
http://support.microsoft.com/kb/829918/en-us
Please let me know the result. Hope this helps.
Regards,
Steve Fan
TechNet Community Support