Anybody else have issues with DVR?

Note: the settings for the DVR recordings are not wrong. I have set the shows to record three minutes over the end of the show, and this still occurs.

Say a show comes on at 8PM -- it is scheduled to record until 8:33 in the menu. However, when I open the video to play it, it only records until 8:20. This doesn't happen every time. It only happens with new, live shows, such as The Office. When recording reruns of old shows, it gets it right 100% of the time, which is pretty annoying, because I told it to record the new show for a reason.

Anybody else have these issues? It seems it mostly has the problem when you are watching something while something is recording, or while two things are recording -- but sometimes it has issues even with only one recording.

Cox wants to charge me $49.99 to come out and look at the issue, but I don't want to pay it if everyone else is having problems.