@Sango Chan
Check your computer with
ad-awareor
spybot for any spyware.
Go to the windows control panel, internet options, connection tab. Then choose your dial-up connection, click on settings and disable any proxy server. Do the same with LAN settings.
If it still detects a proxy server, your ISP is really using a transparent proxy and you didn't noticed it yet (normally they work only on connections on port 80). You can enter your current online IP in bittornado, advanced preferences in the "Local IP" field, so bittornado submits your IP to the tracker and you should get a green light (not all trackers support the "local IP" override). You can find your current online or WAN IP if you double-click on the connections symbol in the system tray, then go to the details tab.
@Gackt
Try limiting your upload speed to ~80% of your max possible upstream.