Hello, my brother called me this evening with a problem with his iMac 24' machine. I have been using iMac for years, but have been unable to fix his issue. This evening he put a DVD in to his imac. The DVD was accessed by the iMac, then the screen went grey/white with no graphics or symbols on it. His imac has a wireless keyboard and mouse. At this point he called me for help. So, i asked him to ; 1) re-boot whilst holding the alt (option) key. No joy, back to grey/white screen. 2) re-boot holding the letter C key. No joy, back to grey/white screen. 3) Reboot while holding ALT CMD P and R. No joy, back to grey/white screen. At this point I asked him to switch to a wired iMac keyboard. We repeated all of the above, no joy, back to grey/white screen. The disk in the DVD drive can be heard being accessed, I think the iMac is trying to boot from the DVD, but so far I have found no way to make it boot from the internal hard drive. Any ideas please?