Vista Remote Desktop

I have been using Vista at home, and on my laptop and everything works
perfectly. Recently i switched my work desktop connected to AD domain to
vista as well. However now everytime i remote in from home/laptop machine
that is not joined to AD I get the following error message.

"No Authority could be contacted for authentication. For assistance please
contact your system administrator or technical support."

This does not happen to any other machine that is also joined to AD, or if I
logon into the system with local account (not domain account) or i use
username@ad.domain.name.

Essentially this error only occurs if
1) Connecting from machine not joined to AD
2) using username of Domain\username (like i mentioned
username@ad.domain.name works)

However does not occur if any of these are true
1) connecting to machine joined to AD
2) using local account
3) using domain account in username@ad.domain.name

Does anyone know why this could be happening. it is not a major stumbling
block to type in username@ad.domain.name , but RDP client automatically
savess it as DOMAIN\username and i have to type it in everytime.

Thanks for your help
Badri