Just an idea, but have you pressed the "TNR" button at the top of the remote? This button activates the buttons (including the Menu button) for 990 use. Maybe the CD button was pushed when you were changing settings.
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AvFan
Outlaw 976 | ATI 2005 | M&K 850s Left, Center & Right, Surround-55s, MX-70B Sub | Harmony 950 remote | Panamax 5100 | OPPO UDP-203 | LG OLED55B7