I would suggest you remove both Spybot and Malwarebytes and then proceed with the Scan. Reboot twice after you remove these Anti Virus products. Post back the outcome...!
Nope, did not work. Any other suggestions?
Try uninstalling and Reinstalling McAfee. Run MCPR tool to remove McAfee from the computer. Restart the machine and login to home.mcafee.com to download the installer for McAfee from your Online Account.
Intiate the installation by double-clicking on the installer. Restart if required and check whether Quick Scan is working..!
Post back for clarifications..!