Yeah, I saw that, too. After hearing your story, I am REALLY glad I didn't experiment with it. Sorry.
If you click on 'Folders' there is a new (I'm guessing) option at the very bottom that lets you select which of your folders to designate an 'Empty' link on.
I de-selected all my folders, so I'm back to having only the 'Trash' folder have a 'Purge' option.
I don't know if DH upgraded Squirrelmail, or what. I thought it had been something I had done inadvertantly at some point.