Cannot purchase from Mac App Store ("Connection failure" msg)
Solution 1:
Try this: log out of your iTunes account (within the App Store choose Store > Sign Out), restart your Mac and then try to purchase/download something.
Solution 2:
I FOUND the answer at the link below. The only correction I would add is to do EVERY item that has a blue cross. https://discussions.apple.com/thread/4085819?start=0&tstart=0