Help: flash CS5 crashing and corrupted .fla's

Question

I'm having one hell of a problem and could really use anyone's help who has a good idea.
I am working in flash CS5 on windows 7 64.
I am currently also running into the crash at save problem.  The most recent version of my .fla corrupted about four days ago, which is something I've grown accustomed to (got the wonderful 'unexpected file format' error).  So I went to my backup file- same issue.  I had to go back 12 backup versions to find one that would work (even my backups on external drives when copied back over to the local drive or opened from the external would give this error.  They did NOT give this error a week ago).  But this backup version now crashes on Save, Save As, or if I try to create a new .fla while the backup .fla is open, it crashes.  If I try to open any other .fla while the backup .fla is open, flash crashes.  Sometimes is gets non responsive and needs to close; sometimes it simply sits there, does nothing, SAYS it's running, but will not respond to clicks, minimizing the window, or anything at all and I will have to force quit out.  Sometimes it will crash when simply clicking a library item. 
I have tried the following recommended fixes:
save the file to a new directory- on the rare chance that flash doesn't crash on save (about 1 in 10), and doesn't corrupt and make a new .fla that's 2k in size (about 1 in 4), the new .fla has all the same problems of the original.
change the JAVA environment variable- no help
increase the jvm.ini xmx value - tried 124. 256, 512, no help
open the file using zip and access the xml library assets directly, deleting them until you find a corrupt file- done it.  three times.  to three different versions of the .fla from the backup files.  Flash still crashes.
save out as .xfl - on the rare chance that flash doesn't crash on save, the .xfl is corrupted (2k file size, no library, and for some reason a black square for an icon) about 3 out of 4 times.  The 4th time, the file works no better than any other .fla
update flash player - no help.
update plugins for all browsers and debug versions - no help
update flash CS5 to the most recent version - no help
download and install all windows updates - no help
delete preferences and config folders - no help
The ONLY way I can avoid flash crashing is to go back to a backup version from more than two months ago.  This version will open, save properly, and debug properly without error.
I have attempted and failed at every suggested fix I have found online or on these forums for this cluster of problems I'm currently having.  I have three weeks to the project deadline, and there is no way I can go back two months in the production timeline.
obviously I cannot afford to lose two months of work.  If anyone has any idea what could be happening, I would be exstatic- I'm really at the end of my rope here.  After four days of looking for help and fixes online and on these forums and talking to adobe support on the phone ('we do not handle coding issues' is the only response I get.  gee, thanks for the help), none of the fixes that have been recommended to me have worked.

Answer 1

another update-
I've managed to reconstruct a file from my original corrupted file that will open and is editable (as long as i don't click through the library items too fast- that will freeze and crash flash).  This file is less than 50 megs.
When attempting to publish, export, or test in conjunction with the document .as associated with the file however I end up with either A: no swf produced and an empty report, or B: a 2k swf with a black square for an icon.
debug produces the 'does not contain actionscript' error.
upon failing to publish, export, test, or debug, flash will then either A: freeze B:freeze, then crash, or (my personal favorite) C: continue to function so long as I don't click on any library items, try to open a new file, try to open an old file, try to save, try to save as, try to exit the program, or try to close a file from the window (all of these result in freezing, crashing, or freezing and then crashing.  There is no apparent pattern to what happens).  Also, clicking back and forth between the properties and library panels in the fla file or the as file will, well, sort of overlay the two panels halfway on top of each other and sort of 'ghost' parts of one onto the other.  What I mean is, if the library panel is open and I click over to the properties panel (both are tabs in the same window of the workspace), the properties panel will be completely gray without any of it's usual boxes or text or button, and instead will have the names of some of the previous library items, greyed out, floating in random places that don't directly relate to where they were before.  Basically, it's all messed up.  And at this point the program will either freeze, crash, freeze and crash, or become completely unresponsive and require a force quit (surprise!).
If I gut the fla down to an even smaller size of about 10-20megs, I can avoid most of these problems, although flash is still very slow to open files (20meg file takes a good 90-120 seconds to open), save files (at least 30 seconds to save a 20meg), and generally clicking around and going about my business of editing symbols or typing script is laggy and slow.  This of course doesn't really do me much good, since it requires me to gut 80% of my projects assets.
I can't tell if i'm getting closer or further away from a solution.......