Motu 828 sends audio out from analog s/pdif and light pipe at the same time!

I have an older Motu 828 (I bought it new some years ago)
I needed it for a recording and it started acting really strange,
I have it connected to my old G4 by firewire and ithe host application is DP4.6
Problem: when I set the audio inputs and want to record,
the Motu 828 suddenly begins sending noise out on all the analog channels/ the s/pdif/ and the light pipe simultaneously.
Meanwhile the audio [either playing from an audio channel or from the piano through the analog inputs] is distorted like there is some kind of feedback loop.

If I shut down the application it problem stops , but as soon as I start the program it all comes back.

Something wrong with the unit??

SOmething wrong with the interface??
?? I am puzzled