This does not come with a warranty, you are responsible for any software issues caused by running any of these scans. That being said, I work at an MSP and use these tools daily.
1) Download and run rkill: http://www.bleepingcomputer.com/download/rkill//dl/10/
2) Download and run MalwareBytes (note, do not install pro): http://www.bleepingcomputer.com/download/malwarebytes-a...
3) Download and run combofix (note, you will lose internet connection): http://www.bleepingcomputer.com/download/combofix/
4) Download and run rootkit remover: http://downloadcenter.mcafee.com/products/mcafee-avert/...
5) Download and run Kaspersky Virus Removal Tool: http://devbuilds.kaspersky-labs.com/devbuilds/AVPTool/a...
6): Install your preferred AV...