I had a computer in the pentium 3 days that eventually would not turn on while upright. Laying the case flat (as you would when opening it up to root around loo

I had a computer in the pentium 3 days that eventually would not turn on while upright. Laying the case flat (as you would when opening it up to root around looking for the problem) would allow it to turn on again. Once on it could be set upright and keep running till next boot up. This was only discovered after several months of intermittent frustrating debugging.