Did you literally unplug your network cable from the PC? or disable the connection completely but turning off the network card? Because that's the only way an offline key will work. If you are still connected to the router/modem/etc but simply have no internet access, the key will not work.
I was connected to the modem but no internet access. Thank you for the explaining the problem.
This seems to be the only file that I cannot unzip / extract with winrar. Did sometihng change because it worked about 5 months ago? Thank you.
Have you tried to switch to another file archive software like 7zip or WinZip?