MY DELL GX270 IS NOT SUPPORTIN THE IDE IN HIS BIOS. I HAVE TRIED MY ALL TRICK BUT I CAN'T SOLVE IT PLZ TELL ME THE SOLUTION. WHEN WE ENTERED THE WINDOWS CD IN THE CD ROM. IT INSTALL THE WINDOW. BU

SOURCE: vga driver for dell optiplex gx270

If that machine has Internet access, try using Windows Update. You could also try Dell's site.

Geno

SOURCE: BIOS failure ??? DEll Systems OptiPlex GX270 Series

this may or may not help, try taking out the cmos battery out (looks like a watch battery) and leave for a few minutes then replace, this will reset the bios.

SOURCE: FATAL ERROR MESSAGE/DELL OPTIPLEX GX150 DESKTOP/WINDOWS XP PRO

Optiplex 150 I get a message error loading operating system
can somebody help out there?

SOURCE: selected boot device is not available

I had the same issue with my dell dimension 2400. The issue I was having resulted in the connection to the drive was loose. Try taking off the side of the case, find the drives in question and reseating the plugins. My pc was quite a bit older though and i don't know if this will be your solution, but its worth a shot. You can even try installing a different cable and swapping to another power supply plug.

SOURCE: Dell Optiplex GX270 will not boot from disk

The reason why Windows install/setup is not continuing is it is trying to detect the hard drive.
You might have a faulty disk or the MBR (Master Boor Record) on the hard disk is corrupted or virus infected.
When you go into the BIOS configuration, does the BIOS detect the hard drive? If so this is a good sign. If not the hard disk is probably faulty and needs to be replaced.
Next boot up with a DOS floppy boot disk and the run fdisk /mbr
This will fix the MBR.
Next run fdisk again and delete all the partitions on the hard drive.
You do not need to create a new partition with this DOS disk, this will be done with the Windows XP install.
Reboot the computer and now install Windows XP. create a new partition and format it in NTFS (do not do a quick format).