woohooo.. found it

wasnt anything to do with all that stuff mentioned above :]
Ive had a fun lil debugging session on a copy of planitia, watching ppl die (which is a curiously satisfying process when you watch it happen in code ;] ).. most were legitimate deaths until finally the case of 'Bashar_NL' turned up... He was sitting at home, pretty much full health, low hunger, low thirst, then bam.. dead.
The reason, it turned out, is that he was so well fed that his health went too high for the code and so looped to a huge negative number. The restorative effects of low hunger on planitia are set quite a bit higher than ive tested with before and so i missed that possibility. (Sorry! my bad).
The offending code has now been fixed so that its impossible for your health to go into negative values like that. (Will be in server 1.42.3, which i'll put up tonight).
(thanks to jemrada for forwarding me a copy of the isl to debug)