Weird, Weird, Weird.

I brought his PC back to my house and rebooted it at least 15 times, worked perfectly every time. I also ran several anti-virus, anti-malware, anti-spyware, spaces cleaners, and defraggler. It still booted perfectly every time. Then I went into the BIOS and changed the boot sequence to ONLY boot to the HDD, nothing else. I successfully rebooted, then I ghosted each drive to a backup drive.

I took the PC back to my father-in-laws, plugged in the mouse, keyboard, and monitor only, nothing else (no internet, printer, or sound/speakers). First time I booted it up.... FAIL! Same message he was receiving before. Reboot and select proper boot device or insert boot media in selected boot device.

So I unplugged the mouse and keyboard, the only thing plugged in was the monitor and power plug. That's it! It gave me an warning message that there was no mouse and keyboard, then FAIL AGAIN! WTH!!??

SO, I thought maybe his surge protector or power in that room was bad, so we ran an extension cord from the kitchen. (I plugged the mouse and keyboard back in so I could control the PC). Rebooted and FAIL AGAIN. (this is really beginning to T me off!)
At this point I rebooted to the BIOS. I looked at the Boot sequence (I had changed it to ONLY boot to the hard-drive when I had it at my house), but the boot sequence now showed all drives, EXCEPT the HDD. There was no HDD even available to select!! So I went to another tab that showed all of the PATA and SATA ports and what was connected, but all of the PATA ports were empty! NO HDD in the list.
I shut it down and opened the case to check all of the connections. I removed every drive connection (CD, DVD, and HDD) and blew in them, then reconnected, but I swapped the HDD and CD drive ports. I rebooted to the BIOS and the HDD was listed. I rebooted and allowed it to finish.
IT BOOTED CORRECTLY TO WinXP!!!
I shut it down and switched the cables back (reverted the CD and HDD).
REBOOTED and it WORKED AGAIN!!!
Shut it down. Switched the power cable back to the Surge Protector and plugged in the Internet, printer, and speakers).
Rebooted it again, AND IT WORKED!!!!!!!!!

IT COMPLETELY baffles me that it:
  • didn't work for him originally at his house
  • worked for me perfectly every time
  • then it didn't work at his house again, not once
  • then it worked for me perfectly every time AGAIN
  • give it back to him and it doesn't work AGAIN, until I switch the cables (but why did it work for me??)


I just don't get it, and not even confident that switching the cables was the fix.

JUST PLAIN WEIRD

any explanations? I'm dumb-founded! (but my father-in-law couldn't be happier that it works again!)