Vista - RDP stopped working

I use Vista Premium Ultimate as my desktop PC. I have it in a domain. I
have been able to RDP into it since I installed it. Then today, for no
reason, when I try to connect to my desktop, it tells me the username or
password is invalid. I know this to be false as I can use those credentials
on any other machine and even OWA. From the Vista console, I can
successfully change the password to any account (verified by using the new
password on any service), but no matter what account I use, it tells me
invalid username or password. The security logs do not show the attempt or
any other security failure. It does not matter from where I try to login or
what account, I get this error. Please help me!