If you're one of the tens of thousands of local fraggers who have been trying to hit up Valve's long-standing shooter franchise, then I'm willing to bet there's a 99.999999% chance you've either seen this happen to someone in your game, or it's happened to another CS:GO fan you know.
It's only limited to Aussies and New Zealanders though -- and it's bloody annoying.
What happens is a series of authentication errors with VAC, Valve's anti-cheat service, that appear to happen to anyone at any time. The error can result in players being kicked from a game and then being unable to rejoin, causing them to abandon official matchmaking games and therefore copping a ban from the service for their troubles.
If you've not been banned for abandoning a matchmaking game before, then the cooldown is pretty short -- usually 10 or 30 minutes. But if you've been struck with the error a few times, the time to queue can blow out to two or more hours, even a full day. It ruins games as well, as the below screenshot neatly illustrates.
If you like a challenge, it can result in some interesting circumstances -- I had one game two days ago that ended up in a 3v4, and my friends and I won a match last night 16-7 after our 5th got booted in the pistol round.
As you'll notice from the second thread, it's not the first time VAC troubles have ruined local Counter-Strike. Players were having the same issues roughly a week ago, with avoiding matchmaking, verifying your game cache and screaming "PLZ VOLVO" into a local Deathmatch server being the only solid advice for dealing with the issue.
A variety of workarounds have been suggested, from synchronising your Windows clock, restarting your computer, deleting Appcache from the base Steam folder and, worst of all, running a plugin to "help with VAC" (as it was described to me). If anyone suggests anything remotely close to the latter, here's a free tip: don't do it. Trying to mess around with anything relating to VAC is only likely to result in a trojan getting installed on your computer, your account being actually VAC banned, or both.
Valve hasn't put out an official statement or acknowledged the issues to date, but I'll update the post if that changes. I've also reached out to the organisers of the $55,555 invitational tournament at Melbourne's Crown Casino this weekend to see if and how that tournament may be affected. There are some a few scattered reports of Europeans and South Americans being affected by the errors this time around too, although it has been largely restricted to the ANZ/Oceania region for now.
Fun fact: Virtus.pro's pasha, a member of one of the two international teams playing at Crown this weekend, was already kicked out of a match at a CS:GO major due to a VAC error. I wonder what the wrath of his biceps would be like if it happens again.