Unable to map network drives.

We have a mixed environment on a flat network. 18 Linux Servers, 22 Windows
servers an AS400. We are not running Domain Services only workgroups. I have
250 Windows PC's running varoius versions some Running Windows 95, some
Windows 98. Most however have been upgraded to Windows XP. All are connecting
to network shares with no issues. I have a Vista Business Machine that will
not connect to Windows network shares nor Samba Shares no matter what I try.
It is a member of the same workgroup as the rest, I have removed all security
software, turned off Windows Firewall, Set Local security policy Network
Security Lan Manager Authentication level to Send LM and NTLM - use NTLMv2
session security if negotiated, NETBIOS over TCP/IP is enabled. Not sure why
this machine won't map out. Any relevant suggestions??