I just learned a quick little lesson. I have a Samsung 830 SSD that I enabled TRIM Support with back on Mavericks or some other OS X version only to discover randomly that Yosemite disables it. So I opened up Trim Enabler and turned it back and on reboot I was met with a greyed out cancel sign: Thus I had to read up that Yosemite does some new security signing thing, and that I should have upgraded to Trim Enabler 3.3 before turning on Trim. In case you get that greyed out cancel sign above read this: http://www.cindori.org/trim-enabler-and-yosemite/ I was able to reverse the problem and no harm was done and now I have Trim Support re-enabled, but it wasn't something I was thrilled about. Oh well, live and learn.