I had the exact same problem on my touring bike and here is a thread about what I found.
http://www.bikeforums.net/showthread...oke-is-a-spoke
I would suggest you are going to keep chasing the problem. I also don’t think you have enough spokes for your weight but with a professional building your wheels back up with quality spokes you may well be ok. The other way to look at it is buying a new 36 spoke wheel readymade you should still have someone go over it and make sure the machine build is ok. In the thread I linked above I found in my case the generic spokes were most likely ok and the problem was in the factory machine building. Then the problem gets compounded with usage and you are at a point where you don’t trust any of the spokes.
I advise everyone I know buying a new bike to request that the wheels are gone over by the bike shop first. And anyone buying mail order find a shop to tension and true before they start using the bike.