I've had many over the years, mostly self induced.
The number 1 computer disaster for me has been the most recent.
Back in March, my self built computer of 5 years started to randomly reboot.
Checked all the obvious such as cables, memory, connectors etc.
The problem would come and go. It finally would not boot at all.
I have been building computers for about 15 year so I've acquired quite a collection
of components for just such an occasion.
The only thing I was short on was power supplies.
Over the years I had fixed friends and families computer and the most common component was the dreaded PS.
Little did I realize that this would be my nightmare.
I tested the PS with a little device that my neighbor gave me that tests various aspects loaded and unloaded.
The PS tested good.
In the end, I toasted 3 motherboards, 2 processors, 6 sticks of DDR memory and a DVD burner.
I finally got out an old 98 machine and hooked her up.
Saved up the pennies and built me a nice shiny new puter with a new power supply.
When it was all done, I checked the old ps again, and it still tested good.
I threw it out anyway.
I lost no data as I back up regularly.
Very expensive and frustrating experience.