Is it excatly every 10 minutes? If so it could be a drop frame issue. Broadcast uses a technique calle drop frame to get a frame rate of 29.97 to line up properly with a 30Hz clock. What this means is that once a minute the timecode jumps by 1 frame, except at minutes divisible by 10. So every 10 minutes there is one extra frame to display. If the video was encoded improperly this could result in a brief glitch every 10 minutes as the video resyncs to the clock. Just a theory, could be something completely different.