Materials are not scaling properly in the material editor?
By default in the newer versions of MAX materials are set to real world sizes instead of scales. Sometimes when reverted back to scale, it sets the scale to 0.001 instead of 1 which makes the material far too small. If you change this back to 1 this should resolve the problem. Reasons why this has happened could be either the units that are set in the file or your system units. Make sure they are metric.