Some of the Ar4 library files are not looking for their images in the correct folders. The result of this is that some materials look like default gray in the preview cube and in the rendering. This occurs even when Ar4 is installed with the option to not to use Ar3 libraries. A fix for this will be included in Service Release 1 for AccuRender 4 when it is released. In the mean time, we have the work-around detailed below.
Here are two examples of materials that contain maps to image files and that do not preview or render correctly.
It on depends whether you have AccuRender 3, too or only AccuRender 4.