Interesting... have a look at this: http://www.thewindowsclub.com/fix-metro-tiles-responding-windows-8
Note the bottom of the page as well. If you have Avast antivirus installed (seems like version 7 is affected?) temporarily disable the program and then try entering the store and running Metro apps again.
If these suggestions don't work, try running the Refresh my PC option (type Refresh into the start screen and select the Settings option at the right. "Refresh your PC" should be the first option you see). The net effect is a repair install of Windows. Any data you have loaded on to the system should be ok, but I would make a backup of anything important before attempting this just to be safe.