This also happened to me a couple of years ago (from a DAZ vendored product). Turned out that the product installed itself to a folder that started with a "$" sign. XML treats that as a special character (for what, I don't know).

After re-naming the offending folder all worked ok.. (Worked it out by tracking down the xml file that had last been changed, since Poser5 wouldn't even start) and yes, it was LibraryPrefs.xml ..)

I did inform Daz, but I don't know if anyone took any notice.

I suspect that some vendors try to get closer to the top of the list than "!!!!!!!!-LOOK AT ME"

Cheers,
Diolma