So your question really has nothing to do with Personal Ancestral File (called PAF for short).
I don't know what the AFT error message means, but I think you would have more success in asking your question in a different forum. Firstly check out the help offered on the web page above. Then, if it doesn't help, try the AFT forum. http://boards.rootsweb.com/topics.software.ancfamtree/mb.ashxhttp://boards.rootsweb.com/topics.software.ancfamtree/mb.ashx
You may need to uninstall the AFT software and re-install it. If you can't resolve your problem, I suggest that you download PAF5 from www.familysearch.org It is free, powerful, easy to use, and I find it totally dependable.
But if you can't export a gedcom file from AFT, you would need to enter your data again.