I'm having the same issue and it's really pissing me off--makes me want to never buy another Miscrosoft product. Everything else in the store is working fine, so it makes me wonder if this glitch is intentionally crafted by MS to thwart users from downloading Chrome and competing with Bing.
seriously, I cant even use anything I was relying on. I need outside programs for school, and the 4 different antivirus updates ive had are pissing me off as well