This morning I was busy on the internet and as something was opening my screen went blank. The pc was still running, I moved the mouse, still nothing. I tried alt/ctrl/del, nothing. Then I tried to restart, nothing, then I switched it off manually. I looked at the cables and found the monitor had somehow become unpluged. I pluged it in and switched the pc on. Instead of booting up I get a message that a registry file is corrupt or missing. I tried inserting the instalation disc and restarting. I get the same message no matter what I try. I can't go into the bios or boot up area as the message appears on everything. Please help.