I signed up for the 22mbps/5mbps Comcast Business Class plan a few months ago and my connection has been mostly fine.
The last few days, I've noticed intermittent slowness+latency that seemed to be getting worse and worse and around evening time Thursday (8/30/2012), I lost all internet connectivity.
My system is connected directly to the Comcast-provided SMCD3G Gateway. I'm able to access the gateway administration page fine, but all other websites fail. I've tried power cycling the gateway several times to no avail. As of this post, I still have no connectivity.
I've attached an image below of the Cable Modem Summary from the gateway. Not an expert on this so I can't identify if any data looks bad.