Outlook 2010: MAPI was unable to load the information service gwmsp1.dll
24th November 2013
If you try starting Outlook 2010 and get an error like this:
“Outlook 2010 cannot open your default e-mail folders. An unexpected error has occurred. MAPI was unable to load the information service gwmsp1.dll”
you can easily fix this problem by going to Control Panel, clicking on Mail, then Show Profiles button.
Remove everything that’s there. Now start outlook again.
Note: removing all the mail profiles will disable your Novell Groupwise client.
If you still want to use non-Outlook email profiles, then the better solution is to manually create a new mail profile for Outlook.
Source: CNET forums.