I have modified the names of some of the folders That's your problem right there. It's not just the obj name that Poser is looking for, it's the entire RunTime trackline. If you rename a folder, Poser can't find it, and bam! there you go. And yes, Poser is that sensitive. It already crashes when you misplace a comma, let alone an entire name. Don't tempt Fate. If the geometry folder is called "millieclothing", leave it alone. The alternative, if you want to risk it, is to go into the obj's text and rename the track there, but I wouldn't do that unless you know exactly what you're doing.