I just posted [FIX] ProjectArchiveFixes-nk to the squeak-dev list. I'd like someone to look it over. I've (minimally) tested project loading and saving (with SketchMorphs read from JPEGs) on Windows, Linux, and Mac OSX, and have also verified that you can load and extract zips using the ArchiveViewer.
I think this should go into 3.4beta ASAP once it's looked at, as otherwise project loading and saving is going to be broken on Win/Mac systems.
squeakfoundation@lists.squeakfoundation.org