Maybe there is a ghost in your computer?
What is your computer running, Mac, Windows or Linux?
Have you run any anti-virus or anti-malware scans lately?
Also, if you have not updated your web browser to the latest version, you can be hacked directly from the browser and nasty things can happen to your browser and your computer.
Firefox (Mac/Win/Linux) is updated at least weekly when security flaws are found, and Safari (Mac only) gets updates about monthly.
I would NOT use Chrome since Google is recording everything you do in the browser and is spying on you all the time. Your privacy is at risk when using Chrome. Chrome also needs regular updates to stay 'secure' from internet threats.