Flash cs4 bug. jpg optimizing (bitmap)
Other CS4 BUG.
BUG APPEARS: when you trying to optimize bitmap in library (changing JPG compression level).
BUG RESULT: Errorous bitmap (disappearing , flickering, blinking,…) in final SWF file or in flash preview.
SOLUTION: Save (with optimized jpg), Close (FLA with bug), Re-Open FLA, Re-publish. Result must be OK.
If you see the same problem with other JPG try again (each time this bug appears do the same operations).