Microsoft Online Services Sign in Tool and BPOS failure solution
We use Microsoft Online Services Sign in Tool to allow Outlook to access Microsoft's BPOS online Exhange and Sharepoint services. I recently had a user reporting that the Sign in tool was reporting "incorrect username or password" even though the credentials were correct.
The solution turned out to be simply un-installing and re-installing the Sign in Tool.
I hope this may be helpful to others facing the same problem.