For the elements with zero allowable stress, did you change the material? You don't have to check the allowable stress checkbox so often as they carry forward. But the zeroes are suspicious. You can send your model to techsupport@coade.com and I will take a look at it to determine what is wrong.
_________________________
Loren Brown
Director of Technical Support
CADWorx & Analysis Solutions
Intergraph Process, Power, & Marine
12777 Jones Road, Ste. 480, Houston, TX 77070 USA