I downloaded Yosemite into my mini (less than a year old and when it restarted I got the screen that asks for the password to icloud and then it blinked and went to the desktop, but.... No screensaver No wifi Error message saying not enough app memory Every input from keys or mouse and the color wheel spins and machine operates as if I memory available. Restarted several times...no change. Checked About this Mac and running Yosemite. I can get into any app or screen but painfully slow response. I have 4 GB memory and 500 gb hard drive and 420 gb available Does anyone have any idea what is happening? I am now running Repair Permissions. 1st message: group differs on "Library/Printers", should be 80. Group is 0 Now showing list of many library/ printer files that have wrong group and "drxw-xr-x but I have dr-dr-X-ray-x" ---------- Probably 100 lines of library/printer files repaired. Now running Verify Disk. Many lines showing up noting problems with "usr/libexec/cups/..... ---------- verifying Volume hung up at "estimated Time 4 minutes" No cursor or key response. Crashing the mini with the power button and force a restart. Nothing to lose.