Issues with sketchup and vray - missing objects in render

[oompa_l]

i am having two issues, which may be related

1. a number of objects (groups) are not showing up in the rendering (vray)
2. i keep setting a material color which then snaps back to some shade of grey. I can finally get it to stick and then when I open the model after shutting down, a bunch of the materials have gone grey again. no clue what's going on with it..

Thanks for your help in advance

[Box]

I've never used Vray so this is only a guess, check that your faces are orientated correctly.
Some renderers don't see back faces correctly.

[valerostudio]

Version of SU? Version of V-Ray? Sounds like an old bug from the 1.7 beta.