Problems Mapping Drives on WinXP Pro Machine on a Windows 2003 Domain

I am having problems getting profiles to automatically map network drives on domained machines. I have the location for their network share set in their profile (\\server\username) but only certain users can get their drives mapped. We have two domains, one is called WIN the other is ACC. The problem is on the WIN domain. The computers they are logging into have the DNS suffixes defined in the TCP/IP properties. The server that the shares are located are also on the WIN domain. If anyone who has had similar problems can give some insight, I would be extremely thankful.