My dell inspiron 1501 laptop is a bit over 2 years old. My 1st power adapter broke after about 2 years. I bought another one ( a dell one on ebay) which broke after a month. I am now using a 3rd party one. It worked fine for a few weeks, but now the battery won't charge, the laptop will only run on AC power. I get an error message during boot up saying the Ac adapter type can't be determined and that the battery will not charge and I will not get optimal performance. I am running winXP home, and I also have ubuntu 8.10 installed as a dual boot. Any help resolving my issue will be greatly appreciated.

99% cases of "unknown AC adapter" issues are connected with wrong or broken PSU. 1% is max8731 faulty(i repaired 2 laptops with this warning, and the problem was with faulty PWM-charger).

Thanks ill look into the warranty on my AC adapter