Have installed yosemite but have a few issues 1. Intermittent wifi - sometimes it connects, sometimes it doesn't, sometimes have to wait 10 minutes - have tried two solutions (new location / delete prefs) but its still a joke 2. Power button no longer sleeps - not sure if this is a new feature? 3. On start up, defaults to secondary screen - which is my TV behind me so now I have to unplug the hdmi out of my tv when I'm done using it / or, turn tv on - go to hdmi 4 / login. (Changing 'arrangement' in display prefs does nothing - it defaults to the second screen). I have a back up off my mountain lion boot , can I revert back to this? Will it mess things up? Is there anyway I can upgrade to mavericks as I've heard it's not a buggy pile of crap like yosemite? We're can I get a .dmg of it?