You could try System Restore to before all this started but if you do that make sure you update McAfee immediately afterwards by right-clicking the taskbar icon and seclecting "Check for Updates".
If that isn't possible, read on.
Follow the steps in this link: Required Reading - Home User Assistance Malware Troubleshooting
If that fails to help install the FREE version of THIS tool, update it and then run. Let it remove anything it finds and reboot immediately if asked to.
(That last tool can be downloaded, updated and run in "Safe Mode with Networking" if for some reason this issue prevents it in regular mode).
When things are all back to normal make sure that Windows, whatever your system is, is totally up to date with all critical and non-critical updates, likewise with your software, browser add-ons etc.