UPnP can be slow and unpredictable at times and this affects all applications that use UPnP (Search google for UPnP, slow, freeze, etc.). It also seems that if UPnP is configured incorrectly on your system, it can cause an application to crash. The issue is further complicated by firewalls, some of which can block UPnP or make it work intermittently. On my system I had to configure my software firewall since it was blocking UPnP UDP by default. To test your UPnP configuration you can use PortForward
, a UPnP testing application.