And here I construed "Fan Death" as death due to fannish activity -- i.e. food and sleep deprivation due to incessantly playing video games, asphyxiation in a fur suit, or cases like the one where a deranged fan killed another player because the latter had beaten him to a super-powered RPG sword.

The hypothermia explanation is wonderful. Do the victims perhaps sleep in walk-in freezers? That's the only way I can see the fan being responsible, short of electrocution. Or perhaps their lungs are so fragile that they collapse as a result of the air movement? :D