Windows 7 on a Mac domain

This is getting a little frustrating as i am trying to join a Mac Domain on a windows 7 computer.

Network setup- Mac OS X Leopard server handles the domain and authentication and file storage of the domain accounts

im trying to join the domain using windows 7 (windows xp and vista work perfectly)

I followed the steps on both links (below) and i still cant connect using windows 7 because it says- "the domain controller cannot be found"

http://support.apple.com/kb/HT3742

http://discussions.apple.com/thread.jspa?threadID=2117232

its seems to be a windows 7 setting, because i can join the domain on a vista or xp computer without any problems.

any thoughts?
thanks in advance
NWT