I have had this unit from comcast for 18 months, or actually different units ,of this model. The first lasted a year, and then problems started. 6 mos ago I got a HDTV and tried to get HDMI connection to work. Never did but in the process they sent out a new box and now I have had 4 different boxes. The more they try to fix things, the worst things get.
So becareful what you do. The comcast tecs don't understand the unit and the quality of the units is getting worse. Actually I would guess it is the software upgrades cause problems.
As you can guess I have lost faith in improving the situation. I don't plan to use any service from comcast that requires a stb, only the qam channels, ofered unencripted. If you want a pvr build a HTPC or go to tivo. I have been configuring my HTPC for 3 months, now and TIVO is starting to look cheap.