Ok,
I ve seen these strange numbers many times while playing SP-variants.
I have seen numbers like 12,456,397 load/quit etc... LOL
Most of the times the problem is connected with big maps and very small intervals between the save/end turn and zip process... I know its sounds weird (again) but the only protection is to wait 3 seconds before doing anything after you press the end turn...
(I speak by experience)
cheers,
Pyros