Hi, Problem 3 seems to happen with all material, however it seems to happen more often with more complex material. If more functions are added to a material, it becomes more likely to behave that way. It also seems to be directly bound to computer-speed, as it happens on my old P-333 at home, but comparable material on my workstation (P-800) work only a little slower. I can send you the materials in question if you want to test it out. As to my "stable" comment: It doesn't really crash, it simply disappears, but without crashing the programm. I can simply restart it and every change I did is still there - just as if I had clicked the "OK" button. But that is actually no problem - it doesn't really crash and nothing is lost. Joerg