Win XP can not connec to Windows server SBS 2003 OEM

Hi –

I would like someone out there to help me to solve is problem that i have been facin since the past few weeks. I have install Windows server sbs 2003 recently but i can get al the xp pro client to connect the server. What i have found that the client found the domain name which it ask for the authorisation bu once enter it give an error msg as following
”
The following error occurred attempting to join the domain “XXXXXXXXXXXX”

(The XXXXX’s are in place of the domain name)

The format of the specified network name is invalid”

Please help
server spec xeon quad prcessor 2gig 200 gig

thank you in advanced
mike