What are the full specs. of the Video Source Files, including their CODEC?
Was the editing done in PrE 4.0 on this computer, or on another computer?
If the same computer, has the OS been changed between PrE 4.0 and PrE 10?
Are all of these PrE 4.0 Projects, that you are Opening in PrE 10, or are you starting new Projects in PrE 10, and just using the same Source Files?
Good luck, and please let us know a bit more,
>red bar in timeline
That means your project does not match your video... what is your project setting, and what is the codec of your file?
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