photoshop elements 10 editor

On Macs the User Library is hidden unless the user unhides it.

So an easy way to get to your User Library is click on your desktop then in the Go menu click the Option key and you'll see Library which is your User Library.

Then you should see Preferences and the files that should be trashed

Adobe Photoshop Elements 10 Settings folder

Adobe Photoshop Elements 10 Paths

com.adobe.PhotoshopElements.plist

Suggest you go to

Macintosh HD/Users/UserName/Library/Preferences

and trash the following folders/files

Adobe Photoshop Elements 10 Settings folder

Adobe Photoshop Elements 10 Paths

com.adobe.PhotoshopElements.plist

Trashing the above files will reset the Photoshop Elements 10 preferences and trash two other files incuding the plist that may have gotten corrupted.

That's a mac error, has nothing to do with PSE.  Your copy of pse is about 14 years old- you are bound to have issues with it.