I had Office 2011 running on my Mac. I had remnants of Office 2008 on it as well and followed these instructions to uninstall Office 2008 completely: http://support.microsoft.com/kb/2500821 

After uninstalling 2008 I discovered the process rendered Office 2011 inoperable (an important detail which was not mentioned in the uninstall instructions).

I reinstalled Office 2011. Word and Excel work fine. When I try opening Outlook 2011 I get "could not change to that identity. An unknown error has occurred in Outlook".  

I should mention while it would be nice to recover my previous identity I can live with just starting fresh with a brand new empty identity since I have my emails duplicated elsewhere.

Here are the steps I've tried to resolve:

1. Updated the new newly installed Office 2011 to the latest version 

2. Used the Microsoft Database Utility to rebuild my identity multiple times

3. Removed all identities in an effort to from scratch with a new identity.

4. Created new identities and tried to open with those

5. Installed Office 2011 again, updated again. Tried above steps again.

No matter what, when I go to open Outlook it throws up a window that says "select an identity" and no matter what I choose, gives me the error message and does not open Outlook.

To reiterate, I don't care about any previous identity . . . I'm just trying to start from scratch with Outlook after installing it.

Any help that can be provided would be greatly appreciated.

Here are my details:

Newest software update for Office 2011 installed (14.2.4)

16GB DDR3

Mountain Lion OS X 10.8.2