I hope this in Windows 7 SP1 and fully updated, including IE10 and add-ons? (Even if you don't use IE it's important it is kept updated as other processes do use it).
Check for problems with McAfee Virtual Technician to see if it finds and fixes the problem: http://mvt.mcafee.com/
Also check for malware using some of the tools in the last link in my signature below. I suggest Stinger and maybe Malwarebytes Free to start with.