I've run into a similar problem when exporting *.3ds files.
My take on this issue is that the 3d window buffer doesn't "flush" properly and keeps on adding to the previous generated 3d view.
My workaround is to physically close the 3 d window, rebuild the 2d one and regenerate the 3d view before exporting.
Quite annoying actually...
This needs to be looked at very soon.
Cheers
Francois
François Chatelain
Worldwide Digital Imaging
Formerly posting as RanXerox
"A little bump will help blur your reflections"