UDP on port 80

[#1]

for the past few days I have been unable to make connections to hosts via UDP on port 80 ?
My computer, router and plusnet firewalls are all off and I have made no changes to my router.
My computer is fine because connections work when I use a 3g dongle. The problem must be my router OR plusnet ?
My router is a standard plusnet thompson one.

[#2]

I just tested (traceroute -q 1 -N 1 -U -p 80 tracker.openbittorrent.com) sending a UDP packet to tracker.openbittorrent.com port 80 and I got a UDP packet in reply. I didn't need to disable any firewalls. Of the other udp port 80 bittorrent trackers listed in the .torrent file I downloaded, tracker.publicbt.com, tracker.istole.it and open.demonii.com all replied, tracker.coppersurfer.tk timed out, and tracker.ccc.de resolved to 127.0.0.1.
Can you give any examples of the hosts you are having trouble with? Perhaps you could try running traceroutes to them.

[#3]

ok tested on other computer (Linux Mint 15) and all seems ok, not sure what has happened to my linux mint 14 box ?
Maybe a bad package update ?

[#4]

reboot fixed the problem !