Well I'm no stranger to weird mac problems. Setting up my machine with the extra SSD and RAM was a nightmare for all kinds of bizarre reasons. That was about 2.5 months ago. Macbook Pro late 2008 Samsung 850 EVO 500GB SSD + Toshiba HDD El Capitan The SSD was running the system and the HDD held my music library. And it was all running very well. Then suddenly one day the computer crashed, and then I was presented with a flashing '?' folder on startup... also I couldn't open recovery mode. Bad news for anyone that doesn't like being locked out of their computer with no explanation. I tried the SSD in the other SATA cable and it was the same. Flashing '?' Folder, recovery mode won't open. So I put the SSD in my friend's macbook. This time there was the apple logo, a loading bar, but it opened up into recovery mode (without me pressing the recovery mode keys). It displayed the SSD as faded. I tried to first-aid but it failed. The drive seems to have been completely corrupted. Now I put the SSD back into my own computer. Recovery mode opens again. So I erased the HDD (because I have everything on there on a desktop HDD anyway) and I re-installed the OS on the HDD. So now here I am up and running on a new OSX install. I don't think I had too much important stuff on the SSD but it will be annoying to have to install and setup everything again (I didn't time machine backup - oops). So I could format the SSD and put this new system on it, but it would be nice if there was a way to get the old system back again, plus I don't know what went wrong with the SSD in the first place. Could it be faulty? Or maybe El Capitan is to blame? Is this a known problem (if so it would be a devastating error with El Capitan)? Any answers or advice? Thank you! EDIT: bare in mind that at no point have I been informed that the SSD is 'corrupted'