I'd bring it back to the LBS you purchased it from and see if they could help you out.I was thinking that there might have been too much tension on the cable which stressed the derailleur.
Unfortunately, I happened to get this from a website and that was 18 months ago so I'd be shocked if anything will be done to rectify the situation.
So the chain being too short is a possibility. I don't have a big front ring, but I do spend a lot of time in middle in front, big in back.