Cannot boot from Dell XP CD

I am currently having a nightmare with my Inspiron 6000. About a month ago we were getting a problem where XP would not start, which I managed to fix but there were still some significant problems. I decided that the best route to solving this was to restore the PC to the factory settings. Windows System Restore was no longer working, so I decided to try the Dell PC Restore before trying a reinstall of XP. That turned out to be a big mistake; the Dell PC Restore failed, and now I get an "NTLDR is missing Press Ctrl+Alt+Del to restart" error when trying to start the PC (it happens just after the POST has finished). Restarting just results in the same thing happening.

I have now tried booting from the Dell XP CD that I created when I first got the PC with the intention of reinstalling XP, and which I've used in the past without problems. I get the "Press any key to boot from CD" message (having changed the boot order so that the PC will try to boot from CD before using the hard disk). After pressing a key, a "Setup is inspecting your computer's hardware configuration" message briefly appears, but then the screen goes blank (dark grey), after a few seconds the CD drive stops spinning then nothing else happens at all, no matter how long I leave it.

I thought I might be able to boot up using a floppy to copy the NTLDR and NTDETECT.COM files (and possibly BOOT.INI if required) to the c:\ drive to bypass the first problem, but when I boot up using a floppy I am unable to access either the c:\ or d:\ (CD/DVD) drives (the error suggests they just aren't recognised). I have run an extended system diagnostic check, and this says everything is fine. I have tried using the same Dell XP CD to boot another PC running XP, and that is fine; I end up at the expected Windows XP Setup screen.

I have been through the Dell support pages, but there is nothing that helps me get around the problem with the CD boot just stopping. There is also nothing to help getting around the problem with other drives not being recognised when I boot from a floppy, which prevents me from copying anything to or reformatting the hard drive.

Any help would be much appreciated. Thanks.

Note that all our data, photos, etc on the PC is backed up elsewhere, so there is no need to worry about losing data. We are just trying to get the PC working again.