Last time I used flash for an urgent commission I discovered a very heavy bug, which did cost me half a day of work and nearly the whole commission. What happened:
I saved a flash file originally created with Flash CS4 as CS3 because the Actionscript programmer did not have a newer version. When I reopened the changed file and typed CMD+S it saved the file without warning. This was momentous: when I re-opened the file, only the library contents did show up, the timeline and stage was empty. Trying to publish the movie again resulted in a program crash. Thus I had to rebuilt the whole flashfile from scratch the next day and calm down a very nervous (and important) customer. Since then I always chose "Save as" and change the format to "CS3", and – how about that! – the file stays intact.
So HOW can a software have a glitch like this be on the market? I would suggest to Adobe that the rework the whole code because flash seems to be very poorly coded. I experienced numerous minor bugs in the last years, but this one beats them all. You save a file and ruin it.
If anybody else has experienced this, I would like them to share their experiences. Not just with me – share them with the people responsible for this. Write to Adobe.