One of the most processor-intensive times for Sketchup is when it is exporting a model to a renderer plugin. You can see this happening on a PC using Task Manager or on a Mac using Activity Monitor.

If your model is particularly complex, it can crash Sketchup at this point. One of the most common causes of unnecessary complexity is importing free models from the Google 3D Warehouse. Often, these are badly constructed, contain huge numbers of polygons or even include broken bitmap paths. Adding in a few trees from 3D Warehouse can cripple a simple model of a house for example.

If you're having problems rendering from Sketchup, it's worth debugging as follows:

• Save a copy of your model
  
• Remove any 3D Warehouse models, try rendering.
  
• If it's a layered model, turn off 50% of your layers, and render. Refine by turning off more layers and going to render, until it works. Then you will need to go back over the turned off layers to work out which elements are causing problems.
  
• If you're struggling to to pin down the offending component, go through your materials, replacing bitmaps with plain colours one by one, and re-rendering.
  

It may be a painful process, but it always works - there is always something causing the block.