I have an assembly in which I am using a manual press that is secured to a base plate.  All of the mates are satisfied but when I close and then re-open this assembly, the mates have problems (both WARNING and ERROR).

Upon re-opening the file, the parts will lose these mates, distorting the orientation of the parts.  It appears as these mating features get changed to other surfaces.  Something as definitive as two concentric holes become questionable when re-opening the file.  It just doesn't make sense.  I have even tried deleting these mates and re-creating new ones.  And it all seems fine at first but after closing and re-opening this assembly, I am back to square one again.

Any input?