Have you changed the paths to the textures or anything? Does it load fine in Poseray or another app? Check the .mtl files for the texture paths and make sure there are no odd characters. Ideally the textures would be in the same directory as TG2.
When you say it rendered fine previously, did you mean in the previous version of TG2, or in other scenes with the latest version (assuming you do in fact have the most recent release)?
- Oshyan