I was testing some refactoring of the reset/reinit code, and found some 
intermittent crashes, especially when re-positioning several times - so I went 
through my changes, and eventually discovered the crashes also occur in HEAD, 
without any of my refactorings applied!

(My changes do seem to make the crashes occur more often, though, see below)

The crashes appear to be memory corruption - sometime the crash occurs inside 
OSG with bad scene data, sometimes before the crash, my C library reports 
non-malloc-ed or free-ed memory being accessed, and the rest of the time the 
crash is in the AI-traffic code, nearly always accessing bad pointers.

My hypothesis is that something in the AI-Traffic code doesn't like being 
re-positioned; if I reset/re-position very rapidly, I don't usually crash, 
whereas if I wait 20-30 seconds at a location, before re-positioning, the crash 
is much more likely. I think this is because this gives the AItraffic code time 
to 'do something', i.e spawn aircraft. (I think the OSG crashes are due to bad 
model-placements or similar, relating to the AI failures - though this is a 
wild guess)

I should add, with my refactorings applied, doing re-position at JFK, wait 30 
seconds, reposition at SFO, is *almost* guaranteed to crash; with HEAD, that 
will crash on the 4, 5 or 6th re-position, usually. (You need to move far 
enough on the reposition, to trigger a tile load, I think - I usually jump 
around KSFO / KJFK / KLAX ...)

Can anyone confirm or deny any parts of this? I'd like to commit my 
refactorings, but not if they introduce a crashing bug. Ideally I'd like to fix 
the real crash - I'll try a valgrind run this evening - but I'd welcome any 
help tracking it down. If other people don't crash at all, that would of course 
be good to know as well!

James

PS - I'm well aware there's other bugs relating to reset/re-position, but 
please don't reply here to discuss them, or things will get very confusing! I 
only care about a crash during or soon after a reset or re-position, for the 
moment.

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