I did a search to see if a virus or malware was related to the issue and found this possbile solution ...if you are using IE.
Try this
Open IE and pull down the Tools menu and select internet options (assuming ie7), open the advanced tab and look for the section titled 'Reset Internet Explorer Settings'. Click 'Reset' and that should be it...
Let me know if this works for you...
Regards,
Andrew
Sources: Microsoft Support