No Audio for Recorded TV - Intermittent Problem

Hi guys.

Sometimes shows recorded on Windows Media Center have no volume when playing them back. It happens to programs on different channels. Everything was working fine for the last year or so.

I'm using a Quad DVB-T Receiver:
>http://www.digitalnow.com.au/dvbtcards.html

I disabled the tuners in Device Manager to test them 1 by 1 with live TV. They all worked normally.

Win 7 64bit

Any ideas? Codec issue?

Thanx.

Can you provide a sample file that gives the problem?
http://www.sendspace.com

I've been deleting the files but will upload the next one. Thanks.