So I've just installed OS X Yosemite on my iMac and having running it for just 10 minutes I seem to be having no end of problems. 1. All seemed to be going well until I opened Safari. It then crashes after 10 seconds. I have to force quit otherwise the beach ball just continues to spin. This happens every time. I've restarted my Mac etc. 2. Thee appear to have been some weird graphical glitches when entering / leaving launchpad. 3. I read online on the apple discussions site to enter safe mode. Well I can't do that because my keyboard now longer turns itself on when turning my Mac on, I have to manually do it, by which point I've missed the opportunity to enter safe mode. Plus the green light on my keyboard no longer lights up when I'm using capitals on the lock screen. 4. I then tried to enter safe mode using the terminal command, however it's warning me that there may be data loss. I don't kmow what to do short of a clean install. Any advice?