I'm afraid the PPM002, PPM003 etc indicates an issue with memory in the internal board. It could also be an issue with the storage drive. The only way to know whether it is the storage drive (software part) or not is by erasing the drive which will delete everything from it. If it is not software issue, then you have to take it to the Apple Store to get the storage/memory replaced.
You have four options in here. First is, buy Disk Warrior (powerful disk utility application)and try to repair your hard disk or recover your files with it. If it is unable to fix the hard drive, then it will at least help you to recover the files that are readable and save them to an external drive. Get it from here : http://www.alsoft.com/diskwarrior/
Disk Warrior is costly. If you don't want to recover any files or if you don't want to wait for Disk Warrior to arrive, then you don't have to buy Disk Warrior. It is not worth it if you don't have any important files/applications. Disk Warrior will not fix it if this is memory issue.
Second is, if you have another Mac and a Thunderbolt/Firewire cable, then you can setup Target Disk Mode and this will allow you to mount the hard drive of this Mac to that like an external hard drive and you will be able to back up your files --> https://support.apple.com/kb/ph10725?locale=en_US
(After backing up,you can reinstall the OS X after erasing the drive.)
Third is, you can erase the hard drive and try to install a fresh version of Mac OS X in it. This will erase everything from your hard disk unfortunately. Boot into the Mac OS X Utilities screen just like you did before (Command and R). In there, select Disk Utility. In Disk Utility, select your hard disk and erase it. Then close Disk Utility and continue installation. This is the quickest solution if you don't mind losing the files in it. This also will not work if the memory or hard drive is failing.
Final option is, you can take the Mac to the Apple Store. They will recover the files using their tools like Disk Warrior or Target Disk Mode and then reinstall Mac OS X for you.
I'm really sorry, but these are your only options left. If you are not satisfied with my service, then please don't rate me bad or poor or OK. You don't have to rate anything if you are not satisfied. Let me know what you think.