As of today, 6.6.15, is there any better explanation as to why some of us continue to experience issues with SSD under Yosemite? I can only get the drive - Crucial MX200 - to mount intermittently and then, in disk utility, a banner pops up saying the disk is locked. The same drive will work in my Akitio external enclosure (Thunderbolt - iMac) but will not allow a change in partition size / number. But it does mount and reads and writes. Is there some bad Ju Ju with an SSD / Yosemite / Mac Pro 4,1?