You need to update your graphics driver or turn off hardware acceleration in teh monitors' options.
More information needed for someone to help... please click below and provide the requested information
-Information FAQ http://forums.adobe.com/message/4200840
What are you editing, and does your sequence match your video?
For CS5 and later, the easy way to insure that your video and your project match
See 2nd post for picture of NEW ITEM process http://forums.adobe.com/message/3776153
-and a FAQ on sequence setting http://forums.adobe.com/message/3804341
When your project sequence is correct, you will not see a red line over your timeline at first import, before you do anything to the 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