Hi All, Since upgrading last night I have had a nightmare with Yosemite. Here are some of the bugs I am currently experiencing. If others have the same please say so.... and any suggestions or fixes would be welcome. Bug 1: Grey bootup screen At the login Menu all I get is grey, boring grey! no new Yosemite background or my current wallpaper no matter how many times I change it. Bug 2: Nearly every reboot or shutdown Crashes. When I initiate a normal shutdown or reboot the MBP does its normal thing shutsdown Apps and goes to a black screen but then a spinning symbol will stay on a black screen and never complete the process. Once or twice it has worked. I have unplugged all accessories just in case something is holding it up and closed 3rd party apps before initiating the shutdown also. Bug 3: Cannot Re-install Yosemite I get an error when trying to reinstall Yosemite, please see below... "OS X could not be installed on your computer. This core storage operation is not allowed on a sparse logical volume group. Quit the installer to restart your computer and try again." Try again doesn't work!! Apart from that its a little laggy and I wished I had stayed on Mavericks Any help much appreciated regards a fresh install as I cant even try that at the moment.