"Xbox Live Marketplace Error Failed to download required Xbox Live Marketplace data.
It turned out the slow internet was because I was using an extension lead between the socket in the wall and the router.
I will investigatemy internet connection as although online gaming is fine, my internet on my computer has been very slow recently.
Also, I have not tried playing a game while the download is in progress, I just watch the download stick at pending or 0/1%.
But i know its not the d/l speed cas i downloaded fable 2 months ago and it was done in less then a day What makes it extra wierd is that I have been able to download two updates and the optional media update just fine.
Also, the other day I was trying to work it out and wen't to something free to test, the first thing I found was xbox community items which downloaded fine, but just as I was getting excited I tried another non-community item and it failed. If your having problems, try downloading them to see if your problem matches mine.