In November 2013 I purchased the Adobe CS6 Master Collection for educational purposes. After using it for a year without any problems I suddenly got the message that my serial is invalid.
I already checked the host file, uninstalled the update manager and tried installing the software on a clean computer with the original DVD. Since I'm unable to contact costumer service by phone (finally hung up after 2 hours of waiting) and since the online chat is unavailable, I'll try it via the forums. Please help me.