First of all check it is not getting too hot .. they get dust in them and the processer will cook and freeze or shut down.
If you need to, go here ..http://openhardwaremonitor.org/ and install the program to check what you're getting. You may have to clean out.
Then turn OFF System Restore .. and do a FULL AV scan .. AND download Malwarebytes Anti-Malware and do a full scan with that too. Let them sort what they have to.
Once it's clean turn on System Restore again.
This is just the first thing to do.