I don't work in Houdini but maybe point you in right direction by telling you it probably has something to do with unit setup or any mismatches therein.
Usually strange things can happen in almost all 3D apps if this has some mismatches.
When importing 3D models try to matchup unit settings in the importer dialog with the ones you have setup in Houdini or vise versa.
It can also be the FBX was not exported correctly and some transformations did not get reset.
In many apps you can draw parametric objects like windows using units and afterwards do non uniform scaling or other transformations on the whole scene and then get problems when not properly reset the model to world units before exporting (leaving in some models that where depend on the local parametric units). This would probably not be correctable without manually setting things right or do a new export of the original model with proper unit resetting.
Regarding the materials, most 3D apps have their own proprietary shader formats, so it is not always compatible, in some cases basic features (if standard shaders where used in host creators app) like bitmap linking's could have some support.
Hope this gets you any closer ;-)
