My wireless connection drops when launch ares p2p or torrent downloader.?

It could be that your ISP does not support peer to peer file sharing programs. I don't know who you use but I'm fairly certain AOL and the other big names are the ones who do this. The you tube thing could be because you have a limited bandwith you are allowed to pull and it might be bellow what your physical connection can actually haul in. The only way to solve this would be to switch ISPs