Resolved Mac no longer boots :S

[mcmacker4]

A long time ago I installed Windows 8.1 on a secondary drive on my Mac Pro 3,1. One day windows said that the trial version was over and that I had to activate windows but I had no activation keys so I left it like that. It said it would restart every 2 hours automatically and that if I wanted it to stop restarting automatically I had to activate it. I was fed up of having to manually select the drive to boot from (Alt key while startup) so I decided to set the Windows drive to default (Ctrl while selecting drive). Some minutes ago I tried to boot to Mac again but something strange happened: The apple logo appeared just as always but something else appeared that wasn't normal, a loading bar. It would load one eighth and suddently disappear. Some seconds later the computer would shut itself down and nothing more. I tried several times but it would alwais do the same.
My theory is that the fact that I set the Windows drive to default messed something up. Now I need to know how to fix it.
Any ideas?

Thanks.

P.D: I'm writing from windows right now since it is still working, the one that doesn't work is the Mac drive.

 

[DeltaMac]

Setting the startup drive to your Windows boot does not (and cannot) cause your OS X drive to fail.
Your symptoms where your Mac shuts down when trying to boot to OS X probably means that your Mac has tried, and failed to boot to the OS X drive (because the hard drive is failing) The shutdown can be a normal result of failing to boot to a failing boot drive.
So, likely the OS X drive is failing (and just a coincidence that you chose to set the Windows drive as the default boot disk.)

If you have OS X Snow Leopard or older, boot to your OS X installer DVD, and run Disk Utility/Repair Disk to check the hard drive. If you have Lion or newer version of OS X, boot using Command-R to your OS X Recovery system, where you can also run Disk Utility.

 

[mcmacker4]

Your symptoms where your Mac shuts down when trying to boot to OS X probably means that your Mac has tried, and failed to boot to the OS X drive (because the hard drive is failing).

Good news: you were right, the drive is failing.
Bad news: you were right, the drive is COMPLETELY failing.

I booted into recoverynb (as you told me) and verified the hard drive. Disk Utility didn't even finish verifying, it simply told me that the hard drive needs to be repaired, so I went ahead and clicked Repair Drive. Didn't even finish, it basically told me the drive was completely broken and that I need to make a backup.

Seems like I'll be needing a new drive pretty soon...

Thanks for your help