I have an old Dell Optiplex that am trying to reinstall XP on. First, I had to replace the hard drive as I couldn't get it recognised at all. I had to reset the BIOS to get it autoconfigured by Dell's Auto-IDE configuration tool, then it wouldn't boot to a Windows XP CD, saying invalid MBR which strikes me as strange as I selected the CD as a boot device. I tried several other CDs,different flavours of XP, same message. It would boot a WIndows 7 DVD or a DOS clone CD, just not XP. So I thought maybe the Windows XP CD first checks the hard drive to see if a previous install exists, and the disk format, so it can write temporary files to it. If it finds a faulty MBR, it throws a wobbly. So I downloaded a low level format tool from Western Digital and formatted the drive to all 0s. Now when I try to boot from the XP CD I get a message "Strike F1 to retry boot" - thats all. I can still boot from a Dr Dos CD. Does the hard drive need some type of formatting in place - eg Fat 32 or NTFS in order to begin the installation process? When I've installed brand new hard drives, I've not needed to do that.

There shouldn't be a need for any kindof partition on the drive for the XP CD to begin installation.

Does your BIOS have MBR protection anywhere? Used to be on older machines and was designed to stop things fiddling with the boot sector unexpectedly, but it usually threw up a warning - not just failed.

As a silly thought, when the boot order is CD first, you arn't getting (and missing) a 'press any key to boot from CD' prompt are you?

As another thought....does the BIOS have a controller type (IDE/AHCI/RAID) option?

BG

The answer was surprising and as often happens in computing, I was barking up the wrong tree.. The DVD drive on the PC was able to boot from DVDs but not CDs. Of course Xp is on a CD and Vista / 7 are on DVD. I found I was also unable to boot from Spinrite, AVG rescue disk, and other boot CDs, but when I burnt XP Pro onto a DVD, I could boot from it just fine. I'll install XP and see if the drive can read CDs even if it can't boot from them.