After I put the PC on hibernate, after a minute the computer automatically turns on. This never used to happen. I have no automated tasks running.

What could be the problem, please help?

Sometimes, you can check to find this problem by putting the PC in hibernate mode and then unplugging your mouse and keyboard from the cpu. If it stays on hibernation, then you know that dust may have been the problem. Sometimes dust will get into the keyboard and/or mouse and will activate the controls.

If this is not the problem, try using anti malware and anti virus scanners to find if you have a virus or spy/ad ware. These can sometimes mess with your files and turn certain things on.

Keep me up to date with the solution. Next time please mention what kind of cpu u have. Ex windows xp compaq presario 6 years old, etc.