NetBIOS Logon Please Help!

have seen this question posted all over the web and on every forum I frequent and I have yet to see someone conclusively answer it! I have a new 2003 domain with AD configured. I cannot logon to the domain unless I use the NETBIOS domain name or by cheating and using the USER@SOMEDOMAIN.COM.
DNS was configured by DCPROMO at the time AD was installed and I have created a reverse lookup pointer for the server. The only answer I have seen posted to this apparently common problem is that it is probably some kind of DNS error and its left at that!!! ARGHH! Someone please help me! I have read every tech book and website I can get my hands on and I cannot resolve this. Thanks, in advance!