Today I noticed for the first time that the volume controls both on my steering wheel and on the command center will not adjust the radio volume up or down. The volume level appears to be stuck mid-level and won't increase or decrease based on my adjustments.

Thoughts?

 

Happened to me too - '08 E550 - after sitting overnight, fixed itself. Weird - even had a little symbol on the nav/audio screen that locked like a speaker with a slash through it - but I can't figure out how to repeat this. Couldn't figure out how to undo it when it happened either - MB must have used some laid off Microsoft programmers to design the COMAND system.