Sync Problem

I have a Pace set top TV Adaptor that works fine most of the time.
However, occasionally, more so since the last software update a few weeks
ago, the picture and sound lose sync, probably due to a reception glitch.
The way I restore sync is to change channels and then return.
My question is, how is sync between sound and vision maintained?
Does the software resynchronise the picture/sound regularly, say, every ten
minutes or so, or only upon first selecting the channel?
If I left it, would it eventually correct itself?

Thanks for any information.

Martin