Most of the cases of Failed-to-save that I've seen were resource related: usually someone ran out of memory or address space. I don't see those problems too much since I went to 64bit and if you're just having a problem with this one import and not other assemblies as well, then, the problem probably traces back to the ProE file.
Question, are you importing the parts with feature recognition or just as dumb solids?
I tried importing with feature recognition and as bodies. In both cases I get the same error.
You may be right though, may be the original parts are corrupt in some way.
I don't know what happened from 5 min. ago, but now SW will save ProE parts both with and without features.