It's not that surprising for a new product to be plagued by issues and it seems like the new Samsung Galaxy Nexus is no exception to the rule. We know that the phone has already make its mark on various countries starting mid of this month, and it looks like UK users have found some problems.
The Verge - ... with reports coming out of the UK that the device's volume is occasionally going to zero uncommanded (a condition sometimes referred to as "mute"). Furthermore, it seems to stick there for several seconds while the device becomes unresponsive, so you can't immediately fix it... but that's assuming you notice it. If you don't, the danger of missing notifications gets a lot higher.
Users seem to be noticing that 2G service is somehow related — the problem is being reported with greater frequency when the Galaxy Nexus is either connected to or in the process of switching to 2G.