Harold, First question, do you export selected parts only or just export? Ive had a hickup a hile ago where I also could not export, but only when I use export selected. when normal export is used, there is no problem.
The other thing you can check is textures? I once had a specific texture that would not export as well?
Oh and what is your PC specs you use for Gmax?
It seems that he's not trying to export, just work on the project.
Harold, you might be experiencing one of Gmax's rather fun "superglitches".
I've run into these a couple of times while working, and they are just unexplainable. It could be anything wrong with the model. You can send it to me if you want and I'll take a quick look at it, but chances are you're SOL. That is why when I'm working I save multiple copies of the same project. Usually divided up into Exterior and Interior, and each is numbered (Interior05, Interior06, Interior07, etc). Save often and you won't have this issue any more. You run into one of these hiccups and you just revert back to an earlier save. Gmax even has a little + sign next to the save button in the save dialog that does this exact thing automatically.
At any rate, check your PMs for my email.