A guide.real.com tracking cookie keeps appearing on my computer.?

All Real.com apps uninstalled. Cache/cookies cleared. Browser set not to accept third-party cookies. Real.com and guide.real.com cookies explicitly blocked in Firefox (my browser). Yet even when I do not visit their site (visiting their site is not a value of any kind), the tracking cookie reappears regularly on my computer. How can I remove whatever they've done here?