More information needed for someone to help... please click below and provide the requested information
-PPro Information FAQ http://forums.adobe.com/message/4200840
Plus, exactly what are you editing?
Codec & Format information, with 2 links inside to read
-read both links in reply #1 http://forums.adobe.com/thread/1270588
Report back with the codec details of your file, use the programs below... A screen shot works well to SHOW people what you are doing
When you render it, or when you export it?