Does the computer's power management software
tell you that the power supply is unknown or does the adapter simply not provide power?
Will the computer run on the AC without charging
or is neither happening. I ask because as it happens, Dell is sending a warranty tech to the boat tomorrow to replace my motherboard. I was periodically getting an error message saying that the 120v adapter was unknown and the battery
would not charge. Didn't matter what I plugged it into. The Dell support people diagnosed a motherboard fault over the phone
and overnighted a replacement to a local tech. (Not bad considering that I bought it in Canada
over a year ago and I'm in SoCal now!)