Popping sound from speakers when changing channel

[strapped for cash]

I recently bought a Panasonic 42" V20 plasma, which is connected via optical cable to my Yamaha receiver.

Obviously this sounds considerably better than the TV's inbuilt speakers, but when I change television channels I sometimes hear a popping sound. It's the same sound you'd hear when connecting a phono input to an amplifier that's already turned on, though it seems entirely random as to which speaker(s) the sound emanates from.

I'm mildly concerned this could damage my receiver or speakers. Can anyone shed any light on why this is happening and, moreover, how to defeat the popping sound? Has anyone experienced anything similar? Am I risking damage to my audio system?

Any insight/suggestions would be much appreciated...

 

[strapped for cash]

For some reason, the new site occasionally substitutes text for an emoticon, so ignore the strange icon in my original post, especially as I'm not sure what it denotes (perhaps it's prophetic and I'm about to suffer a stroke)!

 

[The_Lhc]

The letter "s" in brackets creates that emoticon, I had that one the other day, really quite irritating, especially as it appears to be a hidden one (ie it doesn't appear in the list of emoticons when you press the smiley button at the top of the text field).