Couple of things I would advise you to do.
1. If you have an anti-virus checker on and it's a paid for variant, once it's expired get Microsoft Security Essentials installed. It's free as long as you have a legit copy of Windows and it will never expire. It comes with its own Spyware/Malware checker.
2. Download and install Malware Bytes. There is a free edition which you can use, it just doesn't come with the real-time monitor that the paid for version has and also doesn't update automatically. However the free one is excellent for malware and spyware detection. Run a full scan and see if it picks anything up.
Two tools that are free and excellent in keeping a PC clear of viruses/spyware & malware, however if you ever see any spoof malware pop up while your browsing (google images is notorious for this) saying there is X amount of viruses found do you want to get rid of them never click yes, just close the browser.