From the moment I first installed the yosemite public beta my built in isight camera disappeared. No matter what app I try to use, FaceTime, Skype, photo booth, etc. I get the error that "no camera is installed". When I look in system profiler it also states that no camera is installed and it doesn't appear under USB either. I know it's not a hardware issue because my cam worked fine prior to installing yosemite. I have repaired permissions, repaired disk, SMC reset, PRAM reset, reinstalled yosemite, etc. I have done everything I know how to do and nothing has restored the built in isight camera. Has anyone else encountered this and/or know how to fix it? Thanks. I am on a 27" iMac, 2.7 ghz, 1tb hd, 16gb ram.