I had the same problem, but on a Citrix environment. We tried to reset the Citrix profile for the user and that worked for a month, then the exact problem occurred again. We looked into the code without really finding anything except it just returned false when trying to initialize the NewMessage function in Outlook.
We eventually switched from the 64 bit exe file to the 32 bit exe file and that solved the problem instantly.
Regards,
Brian