My power supply went bad, and a friend of mine with the same notebook had his go bad, too. On both occasions, it was exactly the same problem, but in different locations.
The way the cord was designed (or maybe it is just crappy materials) is virtually assured to fail after a certain amount of time. The cord that goes between the power brick and the notebook is a single insulated conductor wire that has a shield that is the return. The very thin, white insulation does not seem to be a solid rubber sheath like most wire, but is more like a covering that is wrapped around the center wire. If you cut a piece out and look at it, it seems solid enough. However, if you give it a twist, you will see that it begins to seperate, almost like it wants to unravel.
After a couple of times that the cable twists, either by moving it around or wrapping it up to purt it in a bag, cracks in the insulation begin to appear. As soon as one gets big enough so that the center wire comes in contact with the shield, the cable shorts out and stops working.
The brick itself seem designed well enough, as this shorting of its output will not hurt it at all. If it is doing this, you will hear a very faint "ticking" sound coming from the brick. You may have to hold it close to your ear to hear it. It will also get quite warm, even if it isn't plugged into the notebook. If you repair the bad spot in the cable, it will work fine again.
On my cable, the bad spot was right next to the power brick. On my friend's, it was about six inches from the plug that goes into the notebook. I was able to successfully repair both cords (his was a bit uglier) and they have worked great since.
The best advice that I can give is to NEVER let this cord twist in either direction. Based on the two that I have seen, it WILL fail if you you do this.