The flashing and weak IR means you need to change the batteries.

Fixed !
Both problems were related to bad batteries!
It really didn't occur to me to be a battery issue since the new Comcast remote came with two shrink-wrapped batteries....apparently old ones. I read on another site that changing the batteries had fixed similar issues. It worked!
-UMB

Seems like I saw that somewhere on this site too. Now I remember. It was the post right before yours.

Thanks you made it possible for me to change channels with my Xfinity (on demand) silver remote on my Comcast digital tuner NOx, I have lost my lil black remote, and had an extra demand remote.You Good Sir, are Awesome!!

i have two xfinity xr11 remotes. the "b" button that gives you a small screen in the bottom right corner of the tv screen when looking at the guide will not function any longer on either of the remotes. they both stoped working at the same time. seeing how they both stopped working at the same time i suspect it is the box and not the remotes themselves. any ideas?

it worked! thank you so much.

Sometimes, a software update for the cable box might fix the problem. You can check for updates through the cable box settings or by contacting Comcast/Xfinity support.