Windows 7 Slow accessing servers

Trying to figure out why on our Windows 7 machines, when I log in locally, meaning not on the domain (local administrator for example) and then try to UNC to a server, i.e. \\server\share, it sits for a while, maybe 20-30 seconds before it prompts me to authenticate. Yet if I type in the FQDN of the server, i.e. \\server.mydomain.org, the prompt comes right up. If I login locally on any of my XP machines the prompt comes right up without needing the FQDN, so I don’t believe it’s a networking/DNS issue because it works fine on my XP machines, just lags on my Windows 7 machines. Any ideas would be greatly appreciated!