Macbook Pro Early 2011 - SSD - Orphaned inodes

I have a Macbook Pro 15' Early 2011. Last year I changed the disk to put a new Samsung SSD (Evo). Recently my computer was really slow. I rebooted on the recovery partition, and tested my disk with disk utility. It showed a lot of "orphaned inodes".

After a clean install and a few weeks, I had the same problem. So I started thinking the SSD was failing. After another few weeks, I couldn't even boot (prohibitory sign at bootup).

I sent it to Samsung as it was still under warranty. They apparently tested it, and saw no problem at all. They formatted it again and flashed it with the last firmware.

I received it two days ago, did a clean install, and today if I run disk utility, I still have these orphaned inodes.

What can I do? Is the SSD failing, or can it be some other part of my computer?

Thanks a lot!