VSE problem?

I have been trying to connect different shots with Video Sequence Editor, but have run into a problem. I can get shorter versions of my mostly completed scenes, but when I try to add the final one, it will render the sequence but will not play it back. The hard drive lights up for a second but nothing happens. All of the scenes were already rendered and I got it to sequence the final clip but needed to change a filler scene and then it would not work. I saved often and change destination names. I don’t know what to do. Please help.

perhaps that clip is using a codec that is not supported. Be sure you can play all the clips in a media player. As a final resort, use frame sequences.

Also be sure the Anim End frame number is high enough to include that clip.