My boss is having a problem connecting to many wireless networks. She has a Power PC G4 and recently upgraded her OS from 10.3.9 to 10.4.6

She has an Airport Extreme card with Firmware Version 405.1 (3.90.34.0.p18)

She cannot connect to networks in different locations which she was previously able to connect to and can connect to the office network but with a very weak signal.

Any suggestions for how to correct this problem would be appreciated.