More information needed for someone to help... please click below and provide the requested information
-Premiere Pro Video Editing Information FAQ http://forums.adobe.com/message/4200840
Exactly what is INSIDE the video you are editing?
Codec & Format information, with 2 links inside for you to read 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
http://forums.adobe.com/thread/592070?tstart=30 for screen shot instructions
Free programs to get file information for PC/Mac http://mediaarea.net/en/MediaInfo/Download
•What is your exact brand/model graphics adapter (ATI or nVidia or ???)
•What is your exact graphics adapter driver version?
•Have you gone to the vendor web site to check for a newer driver?
•For Windows, do NOT rely on Windows Update to have current driver information
•-you need to go direct to the vendor web site and check updates for yourself
•ATI Driver Autodetect http://support.amd.com/en-us/download/auto-detect-tool
•nVidia Driver Downloads http://www.nvidia.com/Download/index.aspx?lang=en-us