if you can find out the ip address your computer is using, (when you download shareaza calls it 'remote-ip' - thats the address of your computer IT CHANGES EVERY TIME YOU USE SHAREAZA BE CAREFUL) then go to something like advanced-firewall and enter that ip and check the 'force to' box, i did that for a 'both firewalled' prob & it worked. you have to check & see if your address is different next time, the wrong remote-ip address will make things worse!
hope this helps