Simple rollover button in flash (problem) as3

Simple rollover button in flash cs3, publish settings action script 3, flash player 9.

Problem: I have created a simple rectangle button (button symbol). It has up state (Red), over state (orange), down state(Green) and hit. ... simple.
No action script. When i publish the SWF file (flash player 9 - AS3) it has a quick flicker as if it is jumping from down state to up state back to down state again .... a very quick jump. If i save it as flash player 9 - AS2 in the publish settings ...it does'nt do it....it does'nt jump. Does anyone know the reason why?

i have often had this issue when i try to preview certain AS3 files on my own comp. 90% of the time once I upload them to a server and try them they work just fine.