For some reason my PC suddenly won't boot. When I power on I get the BIOS splash screen and then it goes to a black screen with flashing underscore and doesn't go any further. If I try to reboot and enter BIOS (F2) it says entering BIOS then goes to black screen with flashing underscore If I try to go to boot sequence (F8 or F12) it bleeps and then goes to black screen with flashing underscore If I put an Windows 7 Install DVD in - unfortunately this is skipped due to previous setting in BIOS (HDD first) Its running twin SATA drives - if I pull either of the HDD power leads or SATA leads it then says SATA Primary/Secondary (as appropriate) drive 0 not found It then sits on that message The machine is running BIOS Dell A07 I have not made any recent (hardware or software) changes to the machine. I have had the machine several years and installed Windows 7 on it from Microsoft.com back in February - and its been quite happy all of this time. I have not moved the machine recently I used the machine happily last night, shut- down normally. Then today got this problem when I turned it on I am at a loss - it seems that I have a large paperweight at the moment

you could reset the bios to default config, by either jumper switch or pulling the battery for a couple of minutes, it may even require a new bios battery...give that a try, hopeully it will fix the issue. i hate computers! but cant help myself....

If you're unable POST, you aren't going to get into Windows. Clear the NVRAM as suggested above. Windows 7 News!

OK I've fixed it... What with 2x SATA leads & 2x Powerleads - I swapped them around several times. Holding down the power button with the mains disconnected and leaving to stand for a long boot up time (20+ minutes). Eventually one combination spotted one HDD, so I was able to enter the BIOS where I disabled the other drive. Then connected up the correct HDD and rebooted. Ran a scandisk. Rebooted OK. Then reenabled the 2nd HDD in BIOS and connected - its all working now. So not sure what the problem was - however in case anyone else has a similar problem - there is hope :) Thanks to all for their suggestions and help since my initial posting