Update: The issue has been fixed, with AMD and Valve working around the clock - fixing it within 24 hours.
Original article: Yesterday's update to the ever-popular Counter-Strike: Global Offensive introduced a variety of technical changes to the game, and unfortunately, they're causing crashes for AMD users.
Both AMD and Valve are investigating what's happening. In the meantime, AMD recommends based on user reports that you lower your Shader setting to medium. Using Fullscreen Borderless mode may help, too.