You appear to be a Premiere Pro CS5 user with an issue related to that program.
Somehow your thread has gotten into the Premiere Elements Forum and not the Premiere Pro CS5 Forum where Premiere Pro CS5 issues are posted and addressed.
You can repost there or wait for the moderator here to see your thread and move it to the Premiere Pro Forum. Be advised that when you get there be prepared with lots of details of what you are doing, including properties of this video.
When you get to the correct forum, some other information that may help someone help you
What kind of video are you editing, and did you use the NEW ITEM process to match your sequence and video? (see below)
How many hard drives, and how do you have your files arranged? (more below)
The PPro/Encore tutorial list in message #3 http://forums.adobe.com/message/2276578 may also help, with more help in message #5 which has a link to show you how to use the NEW ITEM process
My 3 hard drives for video editing are configured as...
1 - 320Gig Boot for Win7 64bit Pro and ALL program installs
2 - 320Gig data for Win7 paging swap file and video project files
When I create a project on #2 drive, the various work files follow,
so my boot drive is not used for the media cache folders and files
3 - 1Terabyte data for all video files... input source & output export files (1)
(1) for faster input/output if you have 4 drives
- use drive 3 for all source files
- use drive 4 for all output files
And finally, all the other information asked for in the PPro Information FAQ http://forums.adobe.com/message/4200840
As you are using PrPro CS5, and as I see that you have posted there, per the recommendations in this thread, I will Lock this one, so that all discussions can continue in your PrPro Forum post: http://forums.adobe.com/message/6119864#6119864
[Thread Locked - please continue any discussion in the PrPro Forum thread]