I'm sorry to hear that you're having this issue.
I'd recommend going through the setup for the remote. The software allows you to assign volume controls by model number. If a different code is required, you can assign it to each specific button. Is it linked to the TV? Or the sound system?
If this isn't happening with the TV's regular remote, it's likely a settings issue with the universal remote.
With my new LED 40" Samsung TV, everytime I use my Harmony Remote to change volume, the volume "muts" and then comes back on to the new level after a few seconds....
My old Samsung LCD, the vol never "muted" during volume adjustments.
I am running the vol through a Bose system and again, it worked ok with my old Samsung LCD TV