Yes, Poser7 can disappear very quickly sometimes.  It seems like it does this when it should be giving an error or asking for a choice from the user.  I say this because it happened a few times at first but not so much lately.  That tells me I must not be doing whatever it was that was causing it.  I think this version of Poser is still the most usable initial release that I've bought.  I don't think SR1 of version 5 was nearly as good.