Win 2000 Domain

I have 2 Win2000 servers, one act as a domain server and the other one as a member server. I a have problem with Windows XP Pro accessing to Win2000 member server, but no problem with other operating systems. When WinXP Pro user login to the domain,the user is able to access to the member server. But after a while, it get disconnected from the member server. When trying to access again, it prompts for the id and password. Cannot access the member server using the domain user profile. Any idea what is going on here? Pls advise.

thanks