Fried DVR, with a side of ire

My DVR has died. Again. This will make it the fifth Comcast DVR that I've had replaced in the past year or so.

And it's not just me. Last time this occurred (November?), the Comcast rep told me that a lot of people have had this problem and that the company was searching for a new manufacturer (if that last part's true, I'll eat my hat).

What's the average life span of a Comcast DVR?