Could be. Tell us your specs.
More information needed for someone to help... please click these links and provide the
What are you editing, and does your project match your video?
Read Bill Hunt on a file type as WRAPPER http://forums.adobe.com/thread/440037
What is a CODEC... a Primer http://forums.adobe.com/thread/546811
What CODEC is INSIDE that file? http://forums.adobe.com/thread/440037
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
For PC http://mediainfo.sourceforge.net/en or http://www.headbands.com/gspot/
For Mac http://mediainspector.massanti.com/