I've tried to load the very same 3d model - PlatformGenerator - from Jacob Charles Dietz.

It's loading into my Vue 6.50 Infinite build 292350 without problems with all textures applied.

But - i've got Vue 5.11-02 Infinite build 285692 still installed and tried to load this model in Vue 5. But it won't load there either, showing the same error window like yours above.

Then i've tried a few more objects and i've found more, which didn't load with my Vue 5 version and displayed the same error, but did load with my recent Vue 6 version.
Furthermore, in Vue 6 i've made up and saved some simple spheres with base material and different other materials and saved them as Vue 6 .vob-objects and all of those didn't load into Vue 5 and produced this error.

So there must be something different with the .vob-file structure. Maybe it could be reported to the Vue producers, so they could check into this, since it obviously is a problem with object structure/loading/recognition - and that happening even with Vue version being in the same version number range (here Vue 6 Infinite to Vue 6 xStream).