So far this has been a nightmare for me, which has been frustrating me constantly. I am using Dell Optiplex GX280 with Windows XP home edition, which is running a BIOS version A04. Recently, i've rebooted the pc to find out that its not booting. It will get to the Windows boot up screen with the progress bar but only to restart to the same process again, over and over. Frustrated that I am, i've inserted the Windows recovery CD to at least either repair of reinstall the operating system to find out that was not possible. I hit F8 to have the boot options, each of the boot option that I've selected gave me an error saying: "Selected boot device is not available." Right after that, I went to the BIOS setting and did a diagnostic test, which recognized all the Boot devices onboard. Now, I cannot even repair of reinstall Windows XP, because the system is not booting from none of the boot devices.

The surprise is when I removed the hard-drive from the computer and loaded it on into another computer successfully; that's right, there is nothing wrong with the hard drive. After that I was totally puzzled. I found a few pointers online saying that the BIOS start-up block might be corrupted itself and I might need to flash/update the BIOS. I found the detailed instruction on how to create a Boot up disk by downloading the BIOS firmware from the manufacture's website. I did exactly as instructed below:

Download the latest version or your choose version of BIOS file for your computer or motherboard from the manufacturer’s support site. Rename the downloaded file to AMIBOOT.ROM. Copy the file to a floppy disk. Insert the floppy disk to the floppy drive. Turn on the system.

After I did that and powered on the PC to boot from the floppy drive, it gave me this error message: "Non-System Disk or Disk Error. Replace and Strike any key when ready." I did all that, and I kept on pressing [Ctrl]+[Home] to force it, but it did not did any satisfying result.

Desperate as I am, my next attempt is to try the instruction below. Since I want to be ready, in the event it does not work, do you have any solution that you can provide? Please keep in mind that I cannot boot from any of the devices at this moment. My only hope now is to come on with a solution that will work through the Floppy drive, since that's the only drive that affected. Thank you very much for your advice and support in advance.

To create a Windows startup disk, insert a floppy disk into the drive of a similarly configured, working Windows XP system, launch My Computer, right-click the floppy disk icon, and select the Format command from the context menu. When you see the Format dialog box, leave all the default settings as they are and click the Start button. Once the format operation is complete, close the Format dialog box to return to My Computer, double-click the drive C icon to access the root directory, and copy the following three files to the floppy disk:

Boot.ini NTLDR Ntdetect.com