|Many thanks for your speedy reply.|
The motherboard is a Compqa h/p 077ch. The power supply is a Compaq PDP 116 P 250W Part No. 244166-001.
On booting the computer fails to detect my hard drive, some times. I re-start and all is well again. I have been told that this problem may be due to the cmos battery, which I have replaced today or a faulty power supply. Please advise.