Pc running Windows XP Home edition includes service pack 2 version 2002, was custom built by6 company now out of business. Problem is that the start switch when pressed the pc did not boot, switch off power and switch on again, this had to be done a number of times till the system booted up. Now will not boot up. Tried different Hard drive that I know works, but no boot up. Tried new powerpack no boot up. Chip is AMD and written on it in marker pen is either D950 or 0950. All cooling fans working well. When it was possible to boot up system working ok. Any ideas as what is possibly wrong. And is it possible to take the Hard drive out and use an external HD case to read what is on the drive, or will that be lost?