Apple released a supplemental update for OS X 10.10.3 on Wednesday, designed to remedy a video driver glitch that caused some Macs to experience issues during startup.
The update is available in the “Updates” tab of the Mac Store. The update’s description, entitled “OS X Yosemite 10.10.3 Supplemental Update 10.10.3,” says it, “fixes a video driver issue that may prevent your Mac from starting up when running certain apps that capture video.”
The bug first surfaced last week, when some users reported significantly longer startup times from when they ran OS X 10.10.2.
Another issue has been reported, which doesn’t appear to be remedied in this update, in which opening large JPEG files via QuickLook or Preview causes the Mac to crash. We’ll keep you posted if we hear of a fix for that issue.