Sounds like you’ve discovered the same bug as I and several others have.
What appears to be happening, is whenever you copy any content other than plain text or bitmap graphics, the mac is storing it on the clipboard in PDF. For some strange reason PSE just can’t handle that, and several menu disappear and other bizarre happening such as when you try to enter figures in an option field, or rename a layer etc, it jumps straight to the tool commands (using the shortcut keys), so it want let you type anything!
To fix it, copy a piece of plain text (in another application), or if you’re in PSE with a file open (if you got that far) you can make a selection and simply copy it and everything comes right… that is until you copy an object or something in another application.
If that doesn’t work, logout and start it back up again. But that gets a bit tedious!
Good Luck
Jamie