Hi WM,
This, as you know, is almost always caused by insufficient available memory. However it would be nice to know the exact circumstances. For instance, in a mission like T2, Titanic can look OK until it jumps to another environment. It might then disappear completely because the former environment is still using memory and there is not enough left to draw Titanic.
It is more likely, in his case, that his system is not adequate to handle a high-poly object like Titanic.
Even on a good system, lifeboats, benches, etc. tend to become mere shadows when you zoom out.
Regards,
Marty