My pc sometimes starts by itself.On time it started up after several days, I was there when it started so there's no chance of anybody fooling around. I thought it could be a dicky switch, Anybody had the same trouble. Spooky init.
Not quite true - on a modern PC "Off" is only a kind of standby - similar to a VCR, it never goes off until you take out the power lead or switch off the switch (if there is one) on the back of the power supply.
At all other times there is power to the motherboard, and the power switch on the front is only a signal to tell the motherboard and PSU to come out of standby. This is why one should never be plugging and unplugging the internals without switching off the PSU.
This is also how signals such as a modem ring, and other events can be used to "switch on" the PC.