dont worry about ngons...go to persp view...RMB>select all >mesh>cleanup. Then follow Ricks advice

select all>edit>delete by type>history

select all>modify>freeze transform

select all>edit>ungroup (if you have an error message do it through the outliner)

select all>mesh>seperate

close and save.....re open...select all>file>export selection (as an .ma file)...then open a NEW scene....file>import>.ma file

select all = geo only...it may try to export ref planes...if so marquee select your objects.

If this fails..post the .ma file and one of use will be able to look at it. It may just be a corrupted scene, my Spitfire is the same at the moment...

cheers bullet