Nope, I use the same computer, and do nothing different.
It goes like this:
*I sign in with my main e-mail account*
*MSN signs in then signs out less than half a second later*
*I try to sign in again*
*MSN signs in then signs out less than half a second later*
*I try to sign in again*
*MSN signs in then signs out less than half a second later*
*I restart my computer*
*Same thing as before*
*I sign in with a different e-mail address*
*It works*
*I try again with my main e-mail*
*It still doesn't work*
*I sign in with my main e-mail on Windows Messenger*
*It works*
*I try again to sign in on MSN*
*It still doesn't work*
*I am frustrated*