I’m using Outllook for Mac 2011 with the Office365 Exchange server and it won’t open.

I cannot open Outlook. Might be related to a power failure while it was open in the background as it was working prior but when I came back to the machine and found it was shutdown I restarted the system. After re-start the Outlook issue has come up. I see from other threads that the solutions mentioned don't apply with Exchange Server use so not sure what to do. I'm using Mac OS X Version 10.7.5