iMovie on my iPhone4 frames freezing?

I just DL the app other day. Created two new projects. one was only a few minutes long. other about 10 minutes with music. Using videos and a few still pics right from my iPhone.

They came out fine. I uploaded them to camera roll.

I went back and wanted to add one more video clip (the clips are only seconds long) and a pic at the very end of my 10 minute movie project. Now I get freezing frames. and some of my frames the times have decreased and cannot make them longer. Like a few short clips have been shortened and cuts out part of the video clip.

I have uninstalled and reinstalled iMovie and started from scratch. Added all the clips together in order from start to finish. havent even added the music yet and the frames are frozen. I hit play and clip starts out slow and semi frozen.. and I can hear audio running smoothly from each clip but the frame never changes.

Ive alaso made sure all other apps were closed and not running. It worked the first time like a charm. dont know why its messed up now?

any suggestions? really frustrating. I wasnt able to find an answer via apple support communities.

thanks!!!