Hello guys. I downloaded Yosemite GM, used createinstallmedia to create a USB stick with the installer, and clean installed Yosemite (deleting just the Mac partition, and leaving my bootcamp intact). When Yosemite first booted, it did 3 restarts - all of which showed the white Apple logo and then it finally booted into the setup procedure (I suspect the first 2 times it was upgrading the firmware or something). Now, whenever I booted Yosemite, it showed the new boot screen - black with a white Apple logo and progress bar instead of grey with a spinner. What happened next was that I decided I didn't like Yosemite, so I wiped my partition clean and installed Mavericks. The system boots, but when I press the power button, it STILL has the black screen (and if I hold Alt, it shows all my bootable drives with the black Yosemite boot screen, not a grey one like Mavericks). I have since wiped my SSD completely (with disk utility, 1 partition), reinstalled Mavericks, but that damned black boot screen will not disappear. When it boots into Mavericks, then the grey screen comes on and the Apple logo and spinner show. However, for a split second it shows black when booting and not white. Is this something embedded in the firmware? I suspect so, as doing an Internet recovery with cmd + R (to install Mavericks) shows an all black background with a grey globe. At that time, my SSD was completely wiped clean, so there was no OS on any partitions. I have tried messing around in boot.efi to no avail. I just can't get rid of the black boot screen. My Mac is a 13" mid-2014 retina MBP. Does anyone know how to remove this black screen entirely and go back to the grey Apple one when booting up and selecting partitions? I'm not happy at all about this. I don't want Yosemite's "remains" on my system until and if I decide to reinstall it.