Have you removed or changed any thicknesses for materials since you last loaded this cabinet?? If not, what material name is is wanting to add and what is the thickness stated in the missing materials dialog for it? How does that compare to what you have defined currently in your materials database? If the name exists in the database, but the thickness if different, you will get this dialog. Please advise...
Scott, this is happening on cabinets that I added materials for in Build 4. I looked in the material database and the few that I added in build 4 are gone. So when I open the cabinet, I just click add the material and everything seems OK. It's not a thickness issue the material is just not there.