Hello Johan,
are you able to import the original model back?
Are you able to import other model there? How many triangles has the model you want to import in?
Are you able to open the Houdini model in some other app?
Hello Johan, this is really strange.
Do you have some images in your project (in the one where you want to import the model)?
Have you tried the application reset?
How are you trying to import the model? Do you have the RCINFO file next to your model?