I have experienced this also. You need to make sure you are running the latest hotfix for ArchiCAD, and update all other third party tools to the latest versions. If this doesn't solve your problem then you need to make sure your OS and particularly your video card drivers are up to date. If after checking all of these you still have a problem then check that your machines hardware meets all of the minimum requirements in order to run ArchiCAD. I think trying to run ArchiCAD with the bare minimum of harware resources will give you troubles particularly if the file is larger or if you have used a lot of complex gdl objects, eg whb's wc's etc.
