If the oemsetup.inf file doesn't specify a HelpFile, Samba will pass an empty string as HelpFile in the DRIVER_INFO_3 (or DRIVER_INFO_6) structure to the client during Point-and-Print installation and Vista clients will error out with 0x00000057 code upon receiving the structure. As Vista client doesn't like empty strings, it seems to be OK with a null pointer, but I couldn't figure out how to pass a null pointer in the DRIVER_INFO structure to Windows clients. Besides the HelpFile, the problem may also happen if other attributes (DataFile, etc.) in the inf file are empty. Thanks!