Slow and Non-Existant Internet

[Vampyr]

Alright, once again come to you guys for help.

I'm having some crazy internet troubles here at my University with my connection in my dorm room(s)

The other night I took my laptop down to my girlfriends room, and I brought my ethernet cable with me. I hooked it up to her router in her room, and everything was okay. When I brought it back to my room and hooked myself back into my router...bad things happened. When I put the ethernet into my computer, I connected, but no web pages or anything will open. I -think- that the connection is so slow everything times out. It's not my router because my roomate is hooked into the same one, and it works perfectly. It's also not my cable, because when I go -back- to my girlfriends room and hook it up there, it works.

Any help?

Also, even though -my- internet works in my girlfriends room, hers doesn't. It works, but it's so slow it's a pain to do anything, and most websites won't load up all the way, even though my internet and her roomates internet moves fast, like cable should.