The Poser convention on filenames does seem to be a little bit Poser-specific, with the use of the :-character. My own observation as a PC user is that using a PC-style path can really mess things up, but there seem to be ways of getting a mix of the two styles into a Poser file. I've found the CorrectReference utility to be invaluable (see in the freestuff) for making sure that Runtime-relative paths are used. Looking at some of the stuff I've seen in Poser-saved files, I get the feeling that there is some really cruddy code buried in the program.