Internet woes

I've been using Ubuntu 8.04 alongside XP for around a week now.The problems are a couple of days old and I think it was because I logged into XP with my internet connection on and my anti-virus expired. (It wasn't genuine, apparently!)In any case, my Transmission Torrent Client download speeds have slowed to a trickle and I'm not able to go BACK to a previous page on Mozilla Firefox. Plus, whenever I try to open the all-in-one sidebar, Mozilla closes down.Is the problem with my ISP or could it be that a virus on my windows is somehow, miraculously, affecting Ubuntu? 

Enable encryption

Maybe your provider has started to limit torrent traffic. Try enabling encryption in the torrent program.

Do you have a router? If so

Do you have a router? If so maybe the DHCP assigned a new IP to the computer and now the open ports are pointing to the wrong IP. Happened to me alot before I setup my network with static IPs.