I was having Max crashes constantly in a similar fashion to you Johny. I would hit undo when I had DX shaders applied and it would crash. It seemed to be an "out of memory" issue from what I could tell, because I brought up my performance dialog while working and I would see the amount of memory max was using just go up,…
i had that problem with 7, and 8... but 9 seems much more stable to me. whether it's because i'm running 64bit or not, i don't know. i would like it if some talented scripter could write their own normalmapping script though.