Motherboard unable to detect hard drive

Hello,
i just bought a second hand dell computer from market ... when i start my computer it shows UNABLE TO DETECT PRIMARY HARD DRIVE ... and says press F1 to continue and F2 to setup.. When i go to setup it detects the IDE hard drive and then when i quit BIOS setting it boots up normally and the pc is running normal afterwards ... i ve changed the data cable and power cable of IDE but same problem persists ... Can anybody guide me tht its the prob with my mother board or something else like BIOS setting ..