Thanks for the ideas, Sirius, and I hope you're onto something, but I haven't experienced the Gehn 25 Win7 crash anywhere other than Minkata and Ahnonay - ie Ae'gura and Gahreesen work fine.
(I submitted logs back in Jan/Feb and discussed the crashes in the Gehn 25 thread).
(We had crashes in the Cleft, and in going to the spy room, but Tsar Hoikas fixed them.)