ADSL Disconnecting problem

Hi guys, first post (woo!).

I have a most annoying problem:

When I play a game, it is only this one game that does it (Joint Operations) when the level (map) changes, it disconnects my whole internet and I have to restart my PC, if I click my connect icon, it says I'm still connected (but nothing can connect to the internet?), so if I click disconnect it freezes the window. So a restart seems to be the only fix.

Now the only other time this happens is when I download torrents, I can download massive files through my browser fine but as soon as I download a torrent it does the exact same disconnecting thing. Restart is needed.

These are the only things it happens on. I can leave my internet on all day idle, or browse the web all day and it is fine.

My specifications are:

Modem: BT Voyager 100
ISP: AOL (I don't use their browser, I connect through the BT modem dial thing)

System:
AMD64 3800
1gb RAMDDR
Windows XP (SP1)

I don't use a router. I have tried firewall on & off, same problems applies with either.

I've posted this on so many forums and have got no replies. I so hope you guys can fix it. Thanks alot.