Uh oh, sounds like the same problem I had with a Sony Vaio laptop. Looks something like this?
PXE-E61: Media test failure check cable
PXE-M0F: Exiting PXE ROM.
over and over and over.........
This could be one of many things lets try a few.
Try disabling "network boot" in bios (that is unless you boot from a network, in which case let me know) boot pc.
Make sure that CD-ROM is first in line in your boot order in Bios and try booting with windows disk in. In setup screen choose to install windows xp, press F8 at next screen and then press "R" at next screen for a repair install. (this will repair all windows files back to original installation, and you will have to reinstall windows updates, but you will not lose any saved data)
Is your hard drive making funny sounds? (hopefully not)
Can you boot with the cd? Have you made any changes to your pc before this happened? What were they?
Let me know.