how to solve Windows Store problems after the 8.1 update

I might have found what causes the problem with the window store. I live in Greece and I tried to change my region to USA in order to get Cortana.
The store worked fine but when I added the update for additional language support I couldnt connect. I think that s the reason why some people dont have problems (they dont need the extra language support).
After a phone reset on my Lumia 520, I didnt add the Greek keyboard and the store works fine.
So the solution is: Dont install the extra keyboards