I believe 10.10.2 update was automatically downloaded from the App Store and the installation process started at which point the following message was issued: << FreeFileSync prevented update being installed >> presenting Restart and Cancel choices. I pressed Restart button at this point. Normal Update screen with a progress bar appeared. In about 5 minutes the Restarting screen was presented (on a gray background occupying the whole desktop with a changing circle, NOT a Beach Ball, underneath). During the next 25 hours nothing changed the same Restarting screen with this constantly changing circle underneath. At this point I attempted to manually restart the system. Neither mouse nor keyboard actions made any effect; only by pressing and holding the power button for about 10 seconds I was able to restart. A progress bar appeared on a light gray background and in about 5 minutes a normal login screen appeared. About This Mac reports I have 10.10.2 version. Can I be sure this is true? There is no such thing as FreeFileSync among Applications, Widgets or Other (I used AppCleaner application to check this). Activity Monitor shows no FreeFileSync among the running processes. What the hell is this FreeFileSync thing?! Please forgive my ignorance: I am not a software Guru and do need a very simple explanation of what happened and how to fix the problem. Please help!