Ethernet Connection Issue

Hey guys,
I am having issues getting onto the net with my powerbook g4... I am currently using the iBook to write this... same ethernet cable, modem... but doesn't work on my powerbook (recent phenomenon).
I am at my apartment at school... using connection using via ethernet cable connected to the modem...
It works for this comp but not on my powerbook which I believe might be due to a virus on my powerbook. and when I get onto the network on system preference, keeps saying "your network settings have been changed by another application"... and that window keeps pooping up and you can only click okay... then it pops up again... again... again... frustrating the F out of me. If the connection work, it works for a minute or two... cuts in and out...
Any known issues for Powerbook g4 and ethernet connections? or any virus that can cause these symptoms?
Thanks!

Have a look through this link AudMan and you may be able to use one of the fixes quoted:-

Applelinks Discussion Forum | "your network settings have been changed by another application" ...

its talking about mostly the new software update 10.4.11... my situation has nothing to do with virus? that u know of?

Not a virus. I'd try the fixes that harryb posted.