Was my machine accessed unauthorizly?!

I've used Terminal server for a month and everything looks OK. but last
week was really strange. I remotely accessed my office machine at my
home, when I first trying to logon, the error message appear:

"The remote session was disconnected because another user has connected
to the session"
and what is even stranger is that my email (outlook) is opened! I
remembered very clearly that I did turn my email off when I left!

The following day the same error appeared. and one of one sensitive
file is opened. it's just so suspicious!


Which of the following is possible:

1. Terminal server normal manitenance. (Can the maintenance open my
already closed email or file?)
2. Domain administer came in to check my email. (That's terrible)
3. Other person with my login name and password come in. (Terrible
too!)

Greatly appreciated for your inputs!

.