FOUND IT!

Here is a Microsoft Knowledge Base:
http://support.microsoft.com/default.aspx?scid=kb;en-us;299357

The TCP/IP protocol of Windows Server was messed up and needed to be reset.

"NETSH int ip reset c:\path\resetlog.txt"
and a REBOOT.

Squeezebox Server is now running again.

It HAD to be something deeper than just a cfg issue... I never needed to reset the TCPIP in Win Server before. But, this may even explain one more strange thing I was experiencing with AV in Exchange not being able to update after reboot, in several occasions...

Ok, hopefully this is useful for somebody else.