[Serusers] SER and Windows messenger 5

I am trying to register Windows Messenger 5 with SER and am getting the following error: Signing into SIP Communications Service has failed beacuse the service is temporarily unavailable. I've looked at other forums and they suggested that I make sure the domains are the same....I think they are. My user is aisling(a)10.0.1.12 and my server domain is 10.0.1.12..... Any other suggestions as to what the problem maybe?? Many Thanks, Aisling. -------------------Legal Disclaimer--------------------------------------- The above electronic mail transmission is confidential and intended only for the person to whom it is addressed. Its contents may be protected by legal and/or professional privilege. Should it be received by you in error please contact the sender at the above quoted email address. Any unauthorised form of reproduction of this message is strictly prohibited. The Institute does not guarantee the security of any information electronically transmitted and is not liable if the information contained in this communication is not a proper and complete record of the message as transmitted by the sender nor for any delay in its receipt. ----------------------------------------------------------------------------------------