(Unfortunately, you didn't tell us whether this is a laptop or desktop), Please remove the cover from the computer and use compressed air can to blow out all the dust from inside the computer.. Pay attention to cleaning off the processor, the heatsink, the power supply and all fans.. Heat buildup can frequently cause the problem you're seeing.

And when you're done with that, please download, install, update, then restart the computer into Safe Mode. Run a full system scan while in Safe Mode using the tool below and delete all things it finds.

Malwarebytes Antimalware

If you need to download the program on a friend or family member's computer, use the links below to download, then copy them to a CD or flash drive and transfer them to the problem machine and install.

Malwarebytes Download Link (Clicking on the links below will immediately start the download dialogue window.)
http://www.besttechie.net/tools/mbam-setup.exe

Malwarebytes Manual Updater link (To be used to manually update the definitions files AFTER installing the program from the setup file above.)
http://www.malwarebytes.org/mbam/database/mbam-rules.exe

Hope this helps.

Grif