What computer operating system is your Premiere Elements 12 running on? Be sure to update 12 to 12.1 via a project's Help Menu/Update. Background information. For now I will assume Windows 7, 8, or 8.1 64 bit.
Now to the core of the matter and a quick way to find and correct the problem which is related to fragment beyond what you consider to be the end of your Timeline content.
1. Open the project to the Expert workspace. Expand the Timeline content maximally by taking the Zoom Out-Zoom In Slider above the Timeline all the way to the right.
2. Hit the computer keyboard End Key. That should take the Timeline Indicator to the spot where the fragment(s) is (are)..
These fragments typically present as thin vertical black lines scattered among the track contents. Could even be a file that you pushed out of the way when
you were editing and forgot you left it there. Search all tracks.
3. After you find and delete it or them, then use the End Key again to make sure that this time Timeline Indicator stops at the end of your intended Timeline content when you press the computer keyboard End key.
Any questions or need clarification, please do not hesitate to ask.
Thanks to the both of you, thought I was more thorough than I actually was. Very much appreciated!
Sounds like great news of success.
Any questions, need clarification, never hesitate to ask.