Poser 5 clothing objects should work in Poser4 if made correctly and if they do NOT include dynamic hair or cloth. If they rely on shaders for colouring weird things happen with going back a version. If a file has a png and no rsr its either PoserProPack or Poser5. Even money on which these days. The lores versions of M&V 1&2 can use the clothing, hair and textures but NOT the morphs of their high res counterparts. If you are a Mac user you should run everything through MacConvertor before using. If an object will not load, or loads weird pastel colored copies of various bodyparts you have a missing or corrupt obj. OR a cr2 that is incompatible with your version of poser. If using p4, make sure you're are patched up to 4.03 Lyrra