I just started receiving this error code a couple of day's ago.
It started happening when I tried to download the Demo for Diablo 3 to see if I would like to purchase it. After selecting it, the xbox took longer then normal to load it, then this popped up. I tried again, got the same error code. I then went into the Marketplace, and found that other titles were doing it. I don't believe it's a parental control issue, as I tried various titles, from E games, to M rated games. Each gave me the same error code.
I'm not sure if it's a connection issue, because I am able to go onto Xbox Live games such as Black Ops 2 and play with online with no problem. I don't think its interference, but I wouldn't rule it out. But moving the console into the room with the router is out of the question as it's in my room mates room.
I also tried following the step by step solution guide located on this website to try and fix it. Nothing seems to work.
Any and all help would be greatly appreciated. If for some reason my account has been blocked from the marketplace, I will be sad.