change your internet connection with a faster one...but if you can't / your connection is faster enough for your purpose and you don't want to change it, read my esperience below.
it happens also to me that, when i'm home, the game starts loading and stops halfway...Refreshing the page several times should do the trick.
I think that a faster connection doesn'tm cause this problem because I don't have any when I'm at university.
Slow connection can cause also things like "Couldn't connect to server, hit back and try again later" or "Your deck was not saved. Connection failed" when you enter the arena.
Don't worry, go to the main menu and retry.
