I wonder if a firewall is blocking the communication with Adobe. If there's anything more you can tell us about your system/network that might be blocking communication, let us know and we'll try to help.
my system: updated win10 x64. Firewall is eset internet security, but problem persists when inactive, even when unistalled. Tried that already. But i would rule out the firewall as problem, because sometimes after closing an starting Acrobat again, it works. I just checked my firwall rules and log again: nothing is blocked.