[miliantnutcase]

You have malware on your PC that’s triggered alerts on their network causing the block.
In all likely hood your computer is probably part of a bot net and it needs to be cleaned.
visit https://constantguard.comcast.net/

[Boogieman]

Hmm, after checking that link, I think militant is right. The ads are popping up because Comcast is detecting suspicious activity on their network coming from something bad installed on your computer.

If you are infected, this is the process I’ve been using lately with about 95% success to remove viruses and rootkits:

Download Rkill - http://www.bleepingcomputer.com/download/rkill/

Download TDSSKiller - http://www.bleepingcomputer.com/download/tdsskiller/

Download MalwareBytes - http://www.malwarebytes.org/products/malwarebytes_free/

Save all those to some location you will remember, like the desktop, then reboot your computer and hit F8 while it restarts, to bring up the boot menu. Select “Safe Mode with Networking”. Once it starts up, install and run the programs you downloaded, first RKill, then TDSSKiller, and finally MalwareBytes. Let them update if they need to, then scan and remove anything they find.

After that, you can restart, and unless you have gotten a very tricky infection, you should be good to go.

[Graybeard58]

You have malware on your PC that’s triggered alerts on their network causing the block. In all likely hood your computer is probably part of a bot net and it needs to be cleaned. visit https://constantguard.comcast.net/

Poster after poster on Comcast's web site have declared these to be false alarms, after scanning with my own soft ware, nothing is found. Constant Alert is not a program that's on my computer, what I get is a pop up ad for Xfinity Constant Alert, Comcast want's me to down load their program, so they can tell me whether I have a problem or not. The only problem I have is the pop up ad.