Macbook Pro wifi and application issues, everything slow

Hey guys,

So my macbook pro has been giving me a lot of issues lately. It doesn't appear to be one particular problem and it's spread out across applications. Here's my situation:

The wifi connection in my dorm room wont work all of a sudden. It's the schools wifi, so I can't mess with. But my roommate, who also has a macbook pro, is having no problems at all. So I think it's just my computer. It SAYS I'm connected to the internet and has full connection, but it doesn't go through.

Here's the weird thing... I CAN connect to any other wifi on campus just fine. And all ethernet ports work fine.

I'm also having trouble with a variety of applications. My Twitter app, mail wont load anything, Itunes store is slow or doesn't work, the App store wont open, Celtx.....

I think it's all programs that require some sort of internet connection to function. And it's really strange how all these applications still don't work right even when I DO have internet connection (through ethernet or other wifi).

Few notes: I've tried reseting the permissions, and I have 40GB free on my harddrive. It's been happening for a week now, and I've tried rebooting many times. I did a large software update right before it started happening, but I'm not sure if they are related.

What do you think? Is this something I can fix on my own? Or is something damaged on my computer?

HELP!