1. Begin with a brand new Squeezebox Classic V3 (and possibly other models) and server 7.4.1.

2. Complete the setup process. (I used wireless networking with WPA2, and connected to my home music server.)

3. Out of curiosity, locate and select mysqueezebox.com from the menu.

4. It prompts for a username/email address. Change your mind and try to back out.  Surprise, you can't!  (This is a misfeature, but not the critical error.) There is no way to go back to your home music server.

5. Looking for a way out, you scroll down to Help and select it.

6. Read the help message.  When you're done, notice there is NO WAY to exit help mode.  The up/down arrows scroll through the help message, but the left and right arrows do nothing. You can't leave. (This is also a bug, but not the critical error.)

7. In frustration, unplug and replug the squeezebox.  It boots up showing "Now Playing: Nothing". And no other buttons on the remote have any effect. You are stuck. (This is the critical error.)

No way out except to reset the squeezebox ("+" key and power on).