My Lenovo Y50 has these performances: Processor: Intel Core i7 4710HQ 2.5 GHz Graphics: NVIDIA GeForce GTX 860M and Intel HD 4600 I have successfully installed Yosemite and was able to boot into my USB using the following flags: /haswell -f -x -v kext-dev-mode=1 GraphicsEnabler=1 Without those boot flags, the USB would not boot, it would only restart on the spot. So, install finished, touched a bit in "Customize", which might have screwed up things, I don't know. Anyway, when I try to boot up without any bootflags, I get this error: https://i.imgur.com/jVbsybI.jpg When I try to get in with safe mode: https://i.imgur.com/VRn1HMB.jpg I tried doing grafix backup all and it's not doing anything. Yesterday I was able to boot with the default Customize settings, but I had to do grafix backup all to be able to boot in safe mode only, which had massive lag, bad graphics and no wifi. What would a solution to my problem(s)?