Okay, this is really getting me frusterated  . I really love useing G-max to producs models that can be used in FS9 but when I get this error message it makes me think otherwise, basically I save my file normally after I'm done working on my project. Then, sometimes the magically become "failed open file ....etc." What causes this and is there a fale safe way to prevent this. These error are seriously starting to make me quit 3d modeling.

Are you opening the file by doubl-clicking or opening Gmax and then navigating to the correct file?  If you're doing one, try doing the other.

Make sure you haven't changed the file type (*.gmax).  I know that's a noob thought, but you never know.

Also try reinstalling Gmax, as that can clear up several problems.

I am curious about what Windows version you are running and if it is up to date.  We had this issue back in 2002 and again in 2004 between some updates.  There should be plenty of hits on this in the archives.

Also, I recommend doing saves after each milestone or 30 minutes with a version, date and incremental number.  This will minimize losses.

Gmax will do auto backups for you every nnn minutes as one solution.  Secondly, try creating a new scene and then merge you scene into it to clear out extraneous materials.

Hope this helps.