I had something weird happen today. We had a thunderstorm and my computer was off and then all of a sudden it was on. There was a click noise and the system just turned on. It's a desktop and I have defrager and a spyware system to set to run at 3am and this was 530 in the afternoon. It's never done anything like this before. Is it actually possible that the lightening turned the system on, it usually turns it off. I have the computer and house phone plugged into the same surge protector and that didn't shut off. Just found it odd and thought maybe someone had a thought on it. The computer is working fine. I unplugged everything after that happened and left it alone for probably two hours.
Thanks!

Actually your computer is never switched off completely, as part of the power supply is still on stand-by to allow actions like preset functions at a certain time.
So a pulse can indeed start your computer.
But chances are that an incoming pulse destroys your computer, reason why it is always safer to completely switch it off (unplug it) when a lightning storm is coming in.

Erratic power can turn it on. Did the power "blink"?

Certain power supply/motherboard brand combinations are more prone to this. We have a fleet of HPs at work. Simply connecting a power cord that is already connected to the wall outlet to their power supply will often power them up.