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Source engine games error in shaderapidx9.dll · theZedt
This error affects all Source engine based games, including Left 4 Dead 2, Portal 1 & 2, Team Fortress 2. In my case the issue was caused by using LapLink PCMover to transfer stuff from a 32bit (older) Windows PC to a 64bit one. This broke part of WMI, triggering some rather weird errors later down the road.