I have installed the game and tried to run multiplayer - got this error when I try to get into multiplayer menu. I have not logged into gog. Tried to run from luncher and directly the AvP_Classic.exe - same result.

FW is setup to allow the game, Win7 Enterprise x64 SP1

Had same problem twice on four games.

win xp sp3
3.2 ghz
1 gb ram

Same problem
Win 8.1
64 bit
8GB RAM

I had this problem and had to reinstall the game to get it to work. You might be able to get it to work if you start it up through the launcher and let it update. If you do reinstall the game, just make sure not to redownload the game via the "Downloader," because that will remain paused indefinitely.