If you have any McAfee (or any other types) antivirus installed on the computer, then please uninstall it per the developers instructions. Please read below:
The best antivirus, cleaning app, and overall maintenance app for Mac OS is Mac OS itself. All you need to do with Mac OS to keep it secure and running well is to keep it up-to-date and do periodic (about 1x per week) restarts. Other than that, leave it alone. Adding third party antivirus, cleaning, security and other types of maintenance apps to Mac OS adds no additional level of security. The only thing these apps do is have the opposite affect users want. They make Mac OS slow, unstable, generate odd behavior and make Mac OS appear buggy.
If the extension is anything else, it should be okay for now.