This happens to me all of the time too, and there's only one Windows login used on this machine. It's not, at least in my case, multiple accounts logged in.
In fact, the user context that the service is running under is the exact same user context that I am logging in under.
I have mentioned this in the past as happening and have never received a real answer as to why this happens or why you can't put some checks in place to ensure that this doesn't happen.
Bookmarks