Virus affected.

Well scanning it with a decent virus scanner would be your first step (obviously). There is a few free ones online and a few paid ones. You can also scan for malware using this http://www.malwarebytes.org/ .. Try clearing out your temp files too .. an easy application that will do it for you is Ccleaner http://www.piriform.com/ccleaner Without any other info its hard to help you any further to be honest .. Just because your machine is slow doesn't mean its a virus or any kind of malicious files/apps ..

You should update your antivirus and if you're using windows, update it as well. A lot of people don't update their systems and that's why they get them.

I hate if my computer get attacked by virus. I am sure you have installed some kind a software with application name or maybe you have visited website that contain trojan virus. I will clean and reformatted my hardisk right now . That's so dangerous for your data.

Using Ccleaner u can Clean Unused file extensions and Clean ur Registry files.. it also help u more in Increasing ur PC Speed.. I would like to Suggest u one more Software that is "Tune Up Utilities 2013" download this Software and Install.. It will more effective thn Ccleaner..