Macbook gets stuck on Grey Screen, won't boot normally
I too had this problem twice. The first time the system got stuck, and switched itself off. Then later when I was trying boot it got stuck at the grey screen. When I contacted Apple for support, they told me that my harddrive is not working anymore and replaced it. All data lost. The second time when it happened was when I tried to restart the system and it got stuck at the grey screen. I tried removing all the devices connected to the system and switched it back on. This time it worked. Let me know if I can be of anymore help :-)