Very interesting idea on the thickness of the drive. I have the Inspiron 15R (5537) and was using a Samsung 840 EVO disk without a problem until I upgraded to Windows 10. I suspect that upgrading to Windows 10 had nothing to do with the problem. But, moving the SSD in and out of the laptop to do backups may have caused a problem with the seating of the disk. Since then I have tried a zillion reboots, boot settings, etc with no luck. Tomorrow, I will try to add something to the thickness of the SSD and see if that works. The SSD works fine on USB. I also tried a different 840 EVO SSD in the laptop with the same results. Driver and BIOS updates from Dell didn't help. I'm running out of options but I really would like to get the SSD working because it re markedly speeds up the system.