electronic Issue with radio volume and then horn

I have the radio on.  Then a beep occurs.  The volume on the radio goes up.  The controls on the steering wheel will no longer work the radio.  The horn will not work.  I turn off the radio for a minute.  Turn back on and then it works.  It usually does this at slower speeds.  Lexus cannot tell me what it is nor duplicate it.  What is wrong?