Failed login to Windows 2003 server

Can anyone help me with this please…

When my server runs and about 6 to 10 user are already logged on to windows 2003 server. And i tried to login some of the users using windows XP client i get this error message.

Windows cannot locate the server copy of your roaming profile and is attempting to log to your local profile.
Details. Access is denied

When using Windows 98 i don’t get my servers drive mapped.