Alienware freezing when using AC adapter

Hello there,

I am currently having a  problem on my Alienware m15x laptop, I have owned my laptop for 1 and a half years without any problems, then one day it just would not work as it used to. When I turn on my laptop with the AC adapter plugged in, it will not boot windows. If i take it out and try to boot windows using the battery it works just fine. When windows has booted up, if i then plug in the adapter it will freeze my laptop and I have to restart. The only way I can use my laptop is on battery.

My specs are:

 i7 740Q 1.73ghz, Radeon HD 5850, 4gb Ram, 500gb Hard drive

I have downloaded the latest Bios, tried a rebuild and then updated everything and still the same problem persists. I was wondering if anyone has a solution for me or if anyone else is having similar problems? My own guess is that it could be the AC adapter. Any help would be appreciated.

Thanks