Ouch bombdropr... Certainly a complex series of events!! I'm certain I can get you back on track... There must be a disparity between the data in the registry and the actual folders. Although locking up like this has not happened before. Please mail me a screen-shot of your poser library folder-tree in explorer... just the root of it... and of what PBooost does when it starts!! h@horseless-headsmen.co.uk ps1: Oh... you do click the flashing 'runtime' don't you?? ps2: Try hitting 'Enter' at lock-up... there could be a message-box hidden behind the main form? Howard:))