Since it's reporting the error in "Networking::UDP::init", I bet some other process already has a port open that Slimserver wants. Uh, if it were a Unix machine, I'd use lsof to find that program; I think one of the Sysinternals tools will map network connections back to the program that opened them. Alternately, you could try just changing Slimserver's port. (I think you can do that.)