Is anybody else having this issue? We are trying to implement Autocad 2009 SP2 but still have several users running 2006 so we need to be saving all files back to the 2004 version so others can also work on them. We have noticed that when we save some files back to the older version and then reopen them, some data may be missing. We have been able to duplicated this on three seperate computers. It appears to us that it is a bug in Autocad 2009. Any comments?