Recorded programs corrupted on Cisco box

The first few exchanges were within months of each other. Some of the techs that came out were aware that the Contour 1 Cisco boxes were prone to getting error code 2.1.2.1 and other corruption issues. In cases where a playback worked once, but failed later, that would not have been a signal issue, since it had played back correctly once. I've been told that the Contour 2 versions of the Cisco boxes may fix the corruption issue. 

Techs have come out multiple times, and signal strength is good, at the DVR all the way back to the junction box. There is a cable amplifier that feeds to a splitter for cable modem, DVR, and phone.

In some cases after getting an error code 2.1.2.1, after power cycling, I was able to play back a recording, sometimes without issue, sometimes with a skip to end, the most recent a 3 1/2 hour recording that froze up at 2 1/2 hours, that was watched once without issue, then got an error code 2.1.2.1, then the next day it would play but freeze up at 2 1/2 hours. This has been pretty much the pattern with all of the Contour 1 Cisco DVRs we've had.

Doing a web search, I see a lot of reports of issues with the Cisco boxes including at this TV Forum.

It's possible you've had 3 or 4 bad boxes, but it's unlikely.  Typically when people exchange cable boxes several times, they later find there was a signal issue.  An error can occur during playback of a recorded program that's been watched before.  When you press a key on the remote to pause, FF, reverse, etc., the remote sends a command to a Cox server.  When a signal issue is occurring, the DVR waits for a response it never receives.  A signal issue during recording will cause an error at that point during playback.

I've personally experienced erroneously reported recording times of over a thousand minutes.  The cause was found to be a main line signal issue.  When that signal issue was found and corrected, DVR recording and playback issues stopped.  Were the techs that told you the issue was due to the cable box and/or told you Contour 2 would solve your issue contract techs?  Have you ever had an in-house Cox tech check your signal strength at the tap?  If you know the neighbor that shares your tap, ask them if they've had any cable issues.  Even if the neighbor says no, your issue could still be caused by a faulty port at the tap.