Well, SnoopDOS says it tries to open AmiTCP:libs/usergroup.library. This certainly isn't present on WinUAE, but it happily runs without it. So just add an Assign AmiTCP: RAM: to your user-startup and you'll be fine.
Installing AmiTCP (without actually configuring it) will cure it, too, but it is much of an overkill just to get the assign into your startup script.
However you might want to install some programs from AmiTCP:bin like ping, traceroute and netstat and you might need the INet-Handler (TCP: device) for some programs. So installing AmiTCP (or Genesis) might not be a bad idea after all.
Bye,
Thomas