Mac Won't Boot. Help needed I use top-notch MBPRO15 Late 2011 with the latest OSX and all the recent updates installed. I had booting problems before which I managed to solve through command+option+P+R. I'm not sure what exactly caused the problem, but it helped a couple of times. But starting from yesterday I'm failing to make it boot whatever I do with it.

So I'm having this:


I turn on the Mac
Chimes go as expected and the initial login screen appears
I put my credentials and booting progress bar starts up
After like 30-60 secs the progress bar disappears leaving me only with a grey screen.
Two options possible afterwards (i) the screen stays grey for as long as I wait or (ii) the mac reboots leading me to the initial login screen.


When try to go to the Troubleshooter with command+R the sequence is exactly the same. Instead of the Recovery mode I get a frozen grey screen.

If you need any more information to localise the problem please ask.
To fix this try the following:


boot to internet recovery mode by pressing cmdaltR immediately after the start-up chime. Depending on your internet connection the boot process may take several dozen minutes.
open Disk Utility, choose your main volume, verify and repair it if necessary


if you had to repair errors just repeat the step to recheck that all errors are gone
reboot to your main drive
if the problem persists boot to single user mode by pressing cmdS after the start-up chime to circumvent the lockout.
after booting is done just enter 'exit' at the prompt to start to the common Aqua interface.
download Onyx or Yosemite Cache Cleaner
start Onyx
clean system/user caches


or start Yosemite Cache Cleaner
clean system/user caches



** "System" is the name of the start volume in my VM. Your volume name may be different.
restart your Mac