There are so many good antiviruses programs out there, but none of them are perfect. Malware can get past them, through trickery or ingenuity. And if you think you’ve contracted some baddies on your Windows computer, there are other tools that you can use to check your system.
ADWCleaner is one such tool that I commonly use, and you can too, for free. It’s a one-time scan that won’t interfere with your current antivirus. Simply download it, let it scan, and allow it to remove whatever it deems suspicious. It will also offer to disable unnecessary junk software after it locates any malware.
ADWCleaner will need to reboot your computer as it strips all the junk away, and things may be greatly improved afterwards. But if you notice anything wrong after using ADWCleaner, you can always use System Restore to roll back its changes.
ADWCleaner is now owned by Malwarebytes and is available here (currently for PC only): https://www.malwarebytes.com/adwcleaner/ .
PS: another good one-time scan tool is Norton Power Eraser.