The hospital is in the final stages of becoming a separate entity. Until recently we were part of the social welfare dept. and we shared a connection to the internet. The connection was split almost overnight. While our own firewall was already in place, the www cache was not. As some MDs needed access for information, their PCs were configured to go straight to the firewall (ports 80 and 443). The Skype PC was one of those.

According to Skype's firewall FAQ, they use 80 and 443 to sneak out calls if everything else is blocked. That explains how the machine would have been able to pick up knowledge of external Skype installations. The PC was recently reconfigured to go through the www cache, so I guess what we're seeing now is Skype going bonkers because it can't dial out anymore.