Hi all. I have a MBP mid 2010. I changed the Hdd to a 1 GB and installed El Capitan. Everything was running fine for some months but couple of days ago it froze and went into kernel panic on boot and has done so ever since. I booted on the old disk via USB, worked fine. I Can access the new disk but I could not partition, make passive, or anything. Tried to install snow leopard from the dvd that came with it and Got an error saying that I cant install to that disk. So I took the new disk out and put the old one in. Works fine. Then I connected the new one via USB which worked. Now I could make passive and active again. And afterwards I could boot from the USB connected new disk and all was good. Put it back in and Got the same kernel panic again... The kernel panic says Panic CPU 1 caller... User space panic: Assertion failed... Library/caches/com.apple.xbs/sources/xnu/xnu-3248.60.10/båd/kern/kern_s Some memory addresses BSD processes name corresponding to current thread: launchd. Have some more info but must type it in manually... So my question is - I could just buy a new disk but the one with the problem seems to be sort if working. Can anyone explain to me what may be going on and how to fix it?