Please make sure you are all contacting support - they play a vital role in fixing issues - however if you do not contact them, fixing the problem becomes so much harder for the team.
The more information from as many people as possible, the better - so please do continue to contact them :
www.support.ubi.com
If anyone is still getting this problem this is how I fixed it, (I purchased the game from Steam). Put Farcry3.exe in compatibility mode, Windows XP (service pack 3), run as an administrator, disable steam in-game community, disable Uplay overlay and in-game notifications. Launch the game in safe mode (from Uplay). Not sure which of these fixed it for me, but it now works so, who cares?
edit: also running Win 8 with a GTX 670.
No word from staff just "check my signature for help" what a load of unhelpful time wasting , sunday : still not able to launch game. Redownloading in case of corrupted files and its only at 100kb /sec at best!& randomly at that? When steam does 2MB /sec constantly.. soo even if theres a new magical patch out today..and it fixes everything let's say , I wont be playing till monday if im lucky with uplay. The uplay service speed is atrocious.Whats really sad is everyone on reloaded torrents are playing game right now, for free, installed cracked etc yet we have paid and have yet to see anything working legitimately.
(its almost like they [publishers] want it to sell more on consoles by
Screwing pc releases on purpose so that eurogamer can post about oit how amzing farcry did in selling xmillion copies on consoles whoopp)
I finally got a mail yesterday from the support saying a should run their dignostic software san-tool. The fun part is that that didn't work :P haha UBISOFT you win the worst support evver price. Just hope you guys fix this game soon. But you should really invest money in support if you gonna release more unfinished/broken games.
I'm usually a calm and reasonable guy, but this ignorance and responing so late and not even you tools work makes my blood boil. Iä. so tierd of buying games that arn't finnished. That money you get is money i have worked together and i buy a game for some relaxing and fun not for sitting and wait for days to get support and maybe even then be able to play.
i waiting since day one for getting some information of the ubi-team, but i think there is no way. the press rated this game/team to high but today u have to pay to get good ratings. gratz ubi, u spent your money right, but your technical fixed and support sux like the other games of your collection.