Windows 8 - Can't install/update any apps from the store

Question

I can browse the store, but I can't install/Update any App. When I try to install any applications, it says downloading, but the download progress bar won't move a single bit.

In gpedit.msc I've put a "Enabled" value in "Allow Store to install apps on Windows To Go workspaces", but it doesn't change anything. 

Please help me...