I ran into some problems with my newly installed Adobe Premiere Elements 10.
I have created a project and imported and inserted mp4-video files and mp3-audio files. Worked great. I could preview from timeline by pressing play and I could also publish and export the video-file and watching using Windows Media Player.
However, now I cannot do this anymore. Even if I close the project, restart Premiere and start a new project it is not possible for me to preview the video-files or watch the publsihed video-file in Windows Media Player. File opens in WMP but nothing happens when pressing play. Same in Premier when trying to review, pressing play but nothing happens.
What could I have done to cause this behavior?
Depending on where this MP4 came from, you could have a number of possible issues going on. Where did it come from? iPhone video, video from several models of pocket camcorder can be very difficult for the program to work with. Especially if you don't have the latest version of Quicktime from Apple.
That said, when you started your Premiere Elements project, which settings did you select?
Is there a red line on the timeline above your clips? What happens if you press Enter and let the timeline render (the red lines will turn green)?