MAPI was unable to load the information service msoc.dll

I finally found out how to fix that error which is displayed when opening Outlook. I received this error because I had the Lotus Notes connector installed, and didn't properly remove it. I tried uninstalling and deleting all the outlook and Office files I could find, as well as deleting registry entries. Nothing worked until I found the solution, i.e. where that outlook portfolio is stored. It's stored in the registry! Here is the full path, it may vary for you:

What I did was simply delete that whole outlook folder in the registry and Outlook started up without any problems. Note that you should backup your registry before doing any changes. Hope this helps!