Boot Failure, Insert Boot Diskette in A:, Press any key when ready

"First Thought: "Where is the "Any" key"

But seriously though i am trying to figure out a problem for a friend and I get this error message after loading windows xp pro sp1 and restarting. it is not hardware because i have replaced everything, including the motherboard and harddrive. Its not the xp because I have tried several different versions. and its not the bios cause i've been flashing the s$%t out of it. so my question is "What is it?" Here is the current system.

KT4A-V, XP 1800+, 5700xt, 512 (256x2) pc2100, wd1000bb-00caa1, lg dvd-rom, 300w antec.

any suggestions, please help.

Whats it the boot order set to???...........is IDE bus mastering turned on in the BIOS??

hdd 0, all other boot devices disabled...

You do'nt have antivirus monitoring enabled in the bios, do you? that can sometimes stop an OS from rewriting a boot sector onto the hard disk.

disable av monitoring if it is on, boot to recovery console from cd, and do a fixmbr/fixboot.