Hey, I have seen a few people with this same issue have posted... There was a fix posted about downloading "download and install this. Microsoft Download Center after your done restart your pc." I have done this but its done nothing, im still not getting prompted for my Login key and its just going straight to a blank bot window. (yes I have tried a fresh install as well)
download and install this. http://download.microsoft.com/download/2/E/6/2E61CFA4-993B-4DD4-91DA-3737CD5CD6E3/vcredist_x86.exe after your done restart your pc. if its still not working after that then upload a full log as an attachment please.