samba - Jan 2004 - Problem with Windows 2003 accessing Samba 3.0.1

Hi,
     We have been running 2.2.8a on a pair of Sun boxen and we recently 
decided to look at 3.0.1. We have a Windows 2003 server that has been 
working fine accessing a share on the Sun boxes, but when we moved to 
3.0.1 all of a sudden we started getting the following message when 
accessing one of the two boxes:

System error 50 has occured:

The request is not supported

The funny thing is it does this when accessing one box and it works fine 
when accessing its "twin" (configs identical other than netbios name).
Basically the only difference we can find between the two sun boxes are 
the NetBIOS names, IPs and hardware serial numbers; samba source, 
patches, etc. are all the same. We're using "SERVER" auth, and the
logs
don't show anything obvious (to us). Has anyone seen anything like this 
or have any suggestions of things to look at?

Thanks,

Derek