It might be a virus/malware. Boot the computer in safe mode (press f8 when booting), and while in safe mode see if you can get to task manager. Then run virus checkers. Panda Cloud Antivirus, Malwarebytes Anti Malware, and Super anti spyware are 3 good free virus checkers.
You can also download something from microsoft called process explorer. It’s like Task manager but more powerful.