I am running Mac OS X (10.9.5) and Outlook 2011 for Mac. We are running Symantec Enterprise Vault 22.214.171.1245. Up until a few days ago I could login to the Enterprise Vault, now I get the error message of "Microsoft Entourage is not running. Check Enterprise Vault system preference pane for configured email client." Now I go into the preference pane and the only clinet available is Microsoft Outlook 2011.
Entourage never ran on this machine since I just set it up three weeks ago, new in the box.
I do have one caveat, I did install MS Outlook 2013 for Mac but I DID know that EV was not going to work for it, but did not care since I am just testing this out, but I assume its install has broken EV for Outlook 2011.
I have uninstalled and reinstalled the EV for Mac twice.
since you're on EV 11 have you looked at IMAP access to your archive instead of messing with the EV addin? it will work with Outlook 2013 and virtually any email client for Mac.