hard drives not recognized by bios

i am having an intermittent problem with my daughters computer and now it has happenend once with my computer. when i turn the computer on it gets to the last boot screen before windows and i get a message that says either os failure or non system disk error insert boot disk. when i reboot the hard drives are not recognized in the bios. i have to unplug and replug the cables for the hard drive and then everything works. i thought it was the cables but i replaced them with round cables and it still does it occasionally. what could be causing this? hard drive going bad, memory. i just replaced my memory and i ran mam test 86 and there were no errors.

 

How old are the computers ?

 

hard drives not recognized by biod

i built both of them and they are not more than two years old. one is a gigabyte ga7n400 pro 2 mobo with xp 2600 and one is asus a7n8x mobo with xp2200.

 

Change the battery on the motherboard & see if it improves anything.

 

It could also be a glitch in the BIOS. Check Gigabyte's website to see if there is a BIOS update.

 

I had the exact same symptoms with a hard drive that soon died. Eventually, the bios would not recognize it.