This is also known as "high-jacking". Spyware has been installed on your computer via social networking or from email link.
This computer problem can be usually attributed to a hardware issue. Usually its the power supply is dying or in most cases a dirty or defective cooling fan.
This is a another common computer problem. However, this particular issue is a bit more serious; therefore, it needs a few diagnostic steps. In most cases this problems are caused by spyware. To avoid this problem update your anti-spyware program daily.