App Store "Purchased" tab freezing. Can't download redeemed things!

I'm trying to update my OS X 10.6 Snow Leopard to 10.7 Lion and then 10.8 Mountain Lion. I redeemed both the OSs and my purchace screen on the App Store keeps flashing. My items won't download and when they start downloading, they freeze up. Help!!! I need to get this done ASAP and this is extremely frustrating! I've tried as much as I can on my own and any help would be great...