I have been working on a flash project for about 3 weeks now. Until now
everything has been running fairly smoothly;however, I recently noticed that
most of my animations that used tweens will be visible on the first frame and
the last frame but not inbetween. If i double click them to enter the symbol
which contains the tween and then go back to the scene(I did nothing but enter
the symbol) they will work properly.They do not stay that way though: After i
save the project, most of the animations return to their broken state.What is
really strange is that only some are broken and it is usually only moving, not
flashing animations that are broken.I have tried saving as a Flash 8 instead of
cs3 but this does nothing. Also, they remain broken when the project is
published. Please ..I need this for work! : frown;

Without seeing the actual structure it's difficult to figure out what is going
on.

Are you making motion tweens on the main timeline, or are you putting in mc's
that have their own timeline tweens? If the latter, do you have sufficient
'time' (frames) in the main timeline for the mc's to play?

If you use a very small framerate (eg 12 fps, the default) and have
motion-intense mc symbols inserted into the main timeline, a lot of the motion
will be skipped over.

I have the animations inside a symbol. The symbols are input into the main
scene. They all have sufficient space and i am using a 20 fps framerate. A few
animations are motion intensive but most are very simple(An object moving 50
pixels to the left). It fixes it temporarily when i double click on the symbol
but then returns if i reopen it. I have 2 other projects that are very similar
and neither experience this to such a degree.

I am mystified, but don't want to leave you hanging because I may have had something similar happen. Any way we (I) can take a look at it? Can you post an example someplace, or upload a zipped file.

I can email the file to you.