try opening the problematic fla with a different flash pro installation. ie, a different computer.
you can also try opening a fla that opens on a different flash pro installation with the problematic computer.
that way you can determine if it's a problematic flash pro (which sounds likely if previously working fla's suddenly cause flash pro to crash).
if that's the case, reset the problematic flash pro preferences: http://helpx.adobe.com/flash/kb/re-create-preferences-flash-professional.html
Other FLA files will open.. The problematical one won't open on any installation.. I suspect the FLA is the problem, just not sure if there is anyway of opening it to ascertain any errors and fix them, or if the whole thing needs to be redone from scratch
then the fla is corrupt.
you can take a long shot, rename the fla to a rar, and use winrar to repair it. rename it to a fla and try opening. that rarely works but is the best outcome.
you can also unrar the renamed fla and extract some of its assets.
and, if you have a working swf, you can decompile it to a fla using, eg sothink's decompiler.