I can ping the file server I'm trying to connect to, but I cannot connect to it by FQDN or IP address. I get the error:0x80070035 The network path was not found. I have no problems connecting from an XP machine to this server over the WAN.
I've gone into secpol and changed the LAN Manager settings to Send LM & NTLM - use NTLMv2 session security if negotiated. I've also tried it with just Send LM and NTLM responses.
I've completely unloaded the anti virus software (trend) on the client and the server. I've disabled Windows firewall.
This happens from several Windows 7 64-bit machines in my office when connecting to a couple of different Server 2008 boxes over the WAN. Some Server 2008 boxes seems to work just fine.