I upgraded my 2009 MacBook Pro three days ago to Yosemite, and when I asked me if I wanted to encrypt my disk, I said sure why not. But my machine has now been unusable for the last three days. At first I had no idea what it was. Thought the new OS just ruined my machine... But now I think I have narrowed it down to FileVault! The status bar is still only 1/6 of the way! It constantly says "Estimating time remaining..."! Most of the time I have to force my computer to shut down and restart by holding the power button. My only temporary fix is to restart it this way and keep it unplugged, since encyption needs a power connection to start. I have been leaving it on overnight to try and let the encyption happen, but like I said... The progress bar has not moved! Does anyone know what I can do to stop this? I already tried re installing Yosemite and that didn't stop the encyption!