Dir-100 "choke" problem

Hello everyone. I have a very strange problem with my Dir 100 router that I very recently purchased. Because I have two computers at home and only 1 internet connection I used the router to have net on both. I use a ppoe connection. I have correctly installed the router, opened ports for my computer for different applications. When I use utorrent, regardless of how many torrents or speed I am having, the internet chokes. If i have messenger and firefox with 2 sites opened and utorrent, those are the ONLY things that work on internet. Torrents are still going, because I am connected to the peers but as soon as I exit messenger for example I cannot log in again. Same things for the internet sites that I have already opened. Basicaly, when my internet freezes, only the already opened connections work, and I cannot open any other connections. To solve the problem I usually connect to my router from browser and disconnect/connect ppoe again. Sometimes the router does not respond from the browser and I am left with a "waiting for..." message at the bottom of firefox. When that happens I have to unplug and plug again the router. I have reinstalled different Windows, used bittorent and azureus and I still have this problem. It rarely happens even when I don't have utorrent opened, but in very few cases. I have updated firmware and tryed everything and I cannot figure out why it chokes. I really need some help please. Any ideas?