To me this sounds like a memory problem. AND, what I always try to call a "semi crash". What I mean is that because of whatever action Vue goes into a faulty status and produces incorrect results. A faulty saved scene file in your case for example. I had that once when I converted a series of Poser props and #1 Vue crashed something after around 10 imports/savings
and #2 the vobs were faulty and can not be opened in other licenses (beside the fact that even the version that has written them needs ages to open the files). Faulty vobs in my case.

But it happens only after a row of savings in one session in my case, maybe as well  in yours.

What can be done? #1 report it to e-on so that there is a chance that they look into it and find the problem. And #2 more often quit and restart the application so that there is a full reset of memory.

One day your ship comes in - but you're at the airport.