You've accidentally turned on Text Wrap by default. This happens when you choose a text wrap option with no objects selected. If you do it with no file open, it will be the default for all new files, too.
To turn it off, open the Text Wrap panel and deselect the wrap with no objects selected in any existing file showing the the problem, and do it with no files open to stop it from affecting new files.
The "extra frame" you see is the text wrap boundary, and it is being added by default.
Here is a screen capture of the Text Wrap panel:
You must have the button on the left active when you have no objects selected.
Select any objects that should not have the wrap and click the left button to remove it.
If this happens in new documents, close all the files and click the left button to correct for any new files going forward.