May be eventually also some router security feature, seeing your PC connecting to many different IPs in short time, it may block also outgoing traffic? (I had different problem with the CISCO router from ISP, linux version of skype plus the way I use web browser after restart triggered something like "malware DNS attack" pattern and blocked my outgoing (!) DNS communication for a minute or so.. Took me some months to figure out (I didn't really look, as it was just small annoyance). Try to check logs of your firewalls/routers.