samba - Jan 2007 - Unable to Access Samba Server from 64 bit Windows

Hello,

We currently have Samba running on a Solaris server, several Linux 
servers, and a Mac OSX server.   The version of Samba  running on the 
Solaris server is  2.2.8a, and the version of Samba on all the rest of 
the servers is 3.x.

All of our Windows computers, including those running 64 bit versions of 
Windows and Windows 2003 Server can access the Samba 2.2.8a server 
without any problems.

All 32-bit Windows XP systems are able to access the 3.x Samba servers 
without any problems.  However, a 64-bit Windows workstation, and 
several workstations running Windows 2003 server cannot access any of 
the 3.x Samba servers.
I've googled and compared the configuration files on all the machines 
without any luck.

We are going to the Start menu, click on "Run...", and then enter 
\\fileserver, and get the following error message:

\\fileserver is not accessible.  You might not have permission to use 
this network resource.  Contact the administrator of this server to find 
out if you have access permissions.  The request is not supported.

Does anybody know what might be causing this problem?

Thanks,

Daryl