workgroup setting fault?

I got pc running on Win2k (Pro), computer name is ‘James’ and it’s under workgroup ‘A’, uses OfficeXP (2002) application and therefore his logging is without a domain server(‘B’ in here, platform is NT 4)

His email has both MSMail and Internet mail. The MSMail located at domain server ‘B’.

Formerly, when i set that pc to joined the domain ‘B’; he has no problem to access his MSMail. But now, he has problem to access, a log on menu was prompted for id and password!

Anyone know why this is happened? Hope to hear from you asap.

Thanks,
Fion