Judging from my experiences on other sites it could be that a member of the forum has either quit voluntarily or has fallen foul of forum rules of etiquette and been deleted - for being very, very naughty!

Also there have been a number of sad losses of former members that I have read about and perhaps after an elapsed time of non-use their details are erased - and all attached comments/threads? A Mod or Ben the programmer might be able to answer - but I would have thought that in the case of a deceased member - that unless the family have so requested it would be a rather nice tribute to their friendship/expertise in life to leave their comments and threads in the 'living world' for us all to learn from as a legacy?