So here's the story... I was updating my 6 month old macbook pro as requested by the OS which seemed to go fine. However, when my macbook restarted it didn't seem to want to go past the apple screen, even after leaving it for 2 hours. Naturally the first thing I did was to run the disk utility and to try to repair the HD but this seemed fine. When trying to start in safe mode (by holding down shift at the beginning right?) a little grey bar appears at the bottom of the apple screen, starts filling up but then at the half-way point disappears and back to the apple screen with loading circle. I'll be honest and say I'm not great so don't know what to do as my next step. Any suggestions people?