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.