OS X Can't connect to network - Windows & Linux Can

Need some help.

My friend is at a client's trying to connect a Mac laptop to the network.

The client is running 10.3.9 - all updates installed - on his powerbook g4.

The network security is wpa-psk tkip - whatever that means.

OSX is saying that it cannot connect to the airport due to encryption or that the password was incorrect.

Windows and Linux connect to this without issue.

 

I should add that the wireless router is a linksys wrt54gl

any help would be amazing

 

No, it's definitely not as he is at a client's place and they don't have his mac address in the system.

 

Thanks man, I am relaying that info. Not sure if he'll try it as it would involve disrupting the entire network but who knows.

If anybody else has more suggestions, ship it this way.