Re: Mac Pro automatically logs me out immediately after log in??

There's a lot of things that can be
done at this point, but the easiest option
might be to go into the single-user mode
if possible. If you can do a "su passwd" there
to set up a root account - if there isn't one already -
and boot into multi-user mode and login as root,
then you can set up a new admin account
separate from the one that's causing problems.

I'm guessing one of the auto-launch-upon-login
items in that problem account is the culprit.
Similar things can happen in the Win environment
as well.

HTH
-Shin