How often do violins burst into flames?

An item from Reuters, adds to the kerfuffle over incendiary batteries. The story, Sony investigates notebook fire, reports that a battery "caught fire at Los Angeles International Airport last weekend". This reinforced a question that I have been pondering for some time. After the recent, almost certainly over blown security scare, why did the Government allow portable computers on aircraft while banning the carriage of musical instruments?

As far as I can recall, there have been no recent sightings of spontaneous combustion of violins. Yet we get daily reports of exploding batteries. And you don't have to be a terrorist, just a tourist, for this to happen.

For some reason, airlines still allow you to board their 'planes with an unexploded battery. Must be something to do with the relative spending power of PC toting business folks against that of orchestral musicians.