I have an iMac connected to cable modem via AirportExtreme...My finacee has a dell laptop also connected to the airport. When the laptop is online my Imac's internet will work for a few minutes then stop working. It still says Its connected to the airport it just wont connect to the internet. I can join another network and then put my network name and password and it will work for another few minutes then stop working.
When the laptop is off then my iMac will connect and stay connected to the internet no problem.
When the laptop is off then my iMac will connect and stay connected to the internet no problem.