One of the first things you want to do when you think you have a virus on your computer is to make sure that your anti-virus software is up to date. If you don't have anti-virus software, you must get some as soon as possible. I recommend getting AVG from Grisoft. Just look for the 'AVG Free Edition' in the menu.
Once you have either installed anti-virus software or updated your current software, do a test scan of your computer. This test scan will look for viruses on your entire computer. Hopefully it finds where your problem is and fixes it.
In my experience working on computers, there have been many times that I have removed anti-virus software from a computer because it is expired. As an example, if you have Norton Anti-Virus of Norton SystemWorks and you don't have an active subscription, then the software is only slowing down your computer and doing nothing about any new viruses that you may get. Either pay for a new subscription or remove it and install AVG from Grisoft.
If you still have problems with your computer and your anti-virus software hasn't found a problem, then you may be suffering from spyware. Look for another article on this site about how to get rid of spyware and what it actually is.