Wireless problem(?) on my PowerBook

Reason for the ? is because I'm not sure if this is really a problem or not. Whenever I'm at school there are certain places (inside classrooms mostly) I get either of these scenarios:

1. I get no signal whatsoever and my AirPort doesn't even detect the network

2. My AirPort will be able to detect the school's network but when I try to connect it says "<Network name> cannot be found"

3. If I do connect I'll get such terrible 1 bar signal that it's impossible for me to do anything.

Some key facts that you must know:

-EVERYONE else is able to connect! i.e. A student to my left, with the newer MacBook, will have a strong connectivity, and to my right will be student to my right with a Dell and has full strength connectivity. What is the deal here?

-I have a wireless router that I use at home and it connects to it no problems at all for the entire time I've had it. Full strength connectivity.

I have the last generation of the 12" PB 1.5.

 

There is no cover on my laptop and nothing I can think of is impeding the signal. If I'm just outside of the classroom it's fine. It's literally as soon as I walk in I get no signal.