*scratches head*
Is it something that’s always up, even without your browser working? Or is it something that’s only functional when your browser is active?
If it’s always up regardless of your browsing, that’s considered adware or malware and is nuke-able via several programs available on the market (I prefer MalwareBytes).
If it’s only up when your browsing the web, it’s an add-on or browser “helper” object (BHO). Those, too, can be removed. I prefer to “fix” it with Firefox, since IE is worthless as a browser. Firefox with AdblockPlus, NoScript, Ghostery, and CookieMonster will ensure you’ll never see another ad from anyone.
Comcast cannot legally force you to have that adware functioning in order to use their services, so you CAN remove it somehow.
“Is it something that’s always up, even without your browser working? Or is it something that’s only functional when your browser is active?”
Not always up, only when I am on any web page.
It’s a pop up ad from Comcast that has no way to exit out.