Q: A grey progress bar will appear and will load for a little bit and will shut off, what do I do?

TThe most annoying thing is that I've already gotten the hard drive replaced! £140 down the toilet

Sorry to hear that.

I Take it that it resolved your problem?

Either replacing your your hard drive or reinstalling OSX.

uunfortunately not. I've done both this things and still nothing. I'm probably just gonna sell it and get a new system

Hi,

did you buy your computer new or was there another owner?

In my case it seems to be a software problem.

I have read about the same problems with other macs and people have replaced the hard drives with mixed results. As I said earlier, I do not believe every case is hardware failure.

But if you reformatted your drive and installed a fresh copy of OSX with updated patches then it might be a hardware problem but obviously not the hard drive.

In 2007-2008 time frame Apple got a hold of bad NVIDIA graphics cards that acted like this. Apple went 6 months past the warranty in my case to replace it.

I read extensively about the vulnerability known as CVE-2014-6271 or The ShellShock Bash Exploit, and interestingly enough one of the posts mentioned the problem of boot issues.

Here is how to test for the vulnerability and see if you are at risk or have been exploited.

http://mac-how-to.wonderhowto.com/how-to/every-mac-is-vulnerable-shellshock-bash -exploit-heres-patch-os-x-0157606/

I am not sure that was my problem but I was at risk and noticed that the firewall kept turning off as well as permissions changing.

After repairing permissions and updating OS X from Yosemite to El Capitan I do not have the problem anymore and the mac works great!

Supposedly this exploit has been patched in El Capitan but they do give instructions on how to manually do it in older versions of OSX.

Again I am not certain of the problem but hope your outcome is as good as mine.

I am worried about losing photos that are not backed up. Will doing this make me lose everything on my computer?

Hi,

This should not affect photos but can you boot in safe mode and back up from there? Or does your machine not start at all?

my mac keeps shutting down,EVEN WHEN IM TRYING TO FIX IT! >_<

I CAN'T GO INTO SAFE MODE OR ANYTHING!!! ;_;

Thank you so much!!!! It worked. I appreciate those of you out there who give of your time and expertise to help others 

Im having the same problem to the point I can't even get it to start to fix it....

It won't go past  the spinner and this loading  bar at the bottom that gets stuck then it shuts off.

Can you tell me what you did.

I need my computer for school, and I'm so lost  on how to fix this. I would greatly appreciate it.

With much gratitude

I don't know if this works for you but me and my brother are having the same issue. Couldn't repair the main disk yet but we reinstalled MacOs with the OsX Recovery Cmd+R in the second partition of the HD. That way  we could access the disk and made a Backup. One thing is certain, the information is still there and can be recovered. Maybe after the back up we can format the disk and reinstall the OS for a clean fresh and new system.

This is the second time this has happened to me after an operating system upgrade. OS X El Capitan has crapped my system out twice now. None of the suggestions have worked for me yet I'm still searching for a solution.

That problem appears to have no 'repair' solution. You need, yes or yes, to format your HD and install the OS again. Many people here seems to be happy with the solution of changing the HD as if people didn't have any important information in there. So here's the thing, you must save your data somewhere and then reformat your HD and instal the OS again. And there's another thing, the damage can be so awful that the rescue doesn't EVEN recognize the HD to access to the files in any mean or even format it (at least for me). So you need to take out the HD (As if it was easy for a mac) and do everything in other computer as a HD slave.

If you have a partition in your HD, instal the OS there to make it work again, at least temporary, to save all your stuff and format the primary partition fresh and let it as new.... yes it's a pain but it's the only thing I could do.

I had same issue, may be I was lucky, HD drive test was ok, but my HD was full, that was the problem, after I erased some of data, it start up normaly,