trouble conncting my airport extreme to certain wireless networks.

[sonofliberty]

I have a G4 powerbook with an airport extreme card. My house has a wireless router with other pc's connected to it and my Mac connects to it perfectly. However there are some wireless networks that I can not connect to, what usually happens is, I can see the network and sometimes even get a signal strength but everytime it will just say "There was an error connecting to the selected network" I've tried toying with the internet connect program and the network options in sys prefs, but everytime I just can't get online, Can anyone help me?

 

[rman]

My first guess it that those networks maybe pass word protected.

 

[sonofliberty]

The networks are usually at my friends house's and they don't have any passwords