Well, first of all, which Firewall are you using?
I used to use ZoneAlarm, but quickly chucked it because it would make programs that have both incoming and outgoing traffic crash, programs like Firefox, uTorrent, and yes Bearshare and even LimeWire. These processes would ''hang'', so you couldn't even end them from the task manager, and the only way to end them was to do a hard reboot.

Check your Firewall settings, 90% chance it will be that.