Couldn't find that - may have remembered it wrong anyway. In the hopes it will help, here's the new stuff that was in my registry after applying the REG file: HKEY_CLASSES_ROOT.BUM (Default) REG_SZ Photoshop.BMPFile Content Type REG_SZ image/bmp HKEY_CLASSES_ROOT.BUMShellEx (Default) REG_SZ (value not set) HKEY_CLASSES_ROOT.BUMShellEx{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1} (Default) REG_SZ {3F30C968-480A-4C6C-862D-EFC0897BB84B} HKEY_CLASSES_ROOT.BUMShellNew (Default) REG_SZ (value not set) NullFile REG_SZ The format should be followable if you have regedit in front of you. I'd be interested to know if this has come out differently from what you intended. This is Windows 2000 on an account with administrator privileges by the way.