Do you have any files that begin with mapi*.* in your C:\windows\system32\ directory?
I struggled with the Outlook connector for a bit, as we indeed had previous installs of the Novell GroupWise client, but I was finally able to get around it - it has been awhile, but can try to help.
For us - along with uninstalling the GroupWise client, I had to uninstall (Add/Remove programs) the Windows Messaging. I then dropped into the windows\system32\ directory a mapi32.dll, a mapistub.dll, and a mapisvc.inf.