Sometimes when problems pop up for no apparent reason it could be that the preferences files had become corrupted. Here are two ways to reset the preferences.
1. The reset process might be built into your PSE version, as shown in this video:
How to Reset Photoshop Elements Preferences - YouTube
2. If your version does not have the reset option, press and hold Alt-Ctrl-Shift (Option-Command-Shift on Mac) immediately while starting PSE. The timing is critical; you may have to try this several times. A dialog box will pop asking if you want to delete the settings file? Click YES.
Let us know if either of these works for you.