P1000 Intercom; Strange Problem

Well this one has me stumped. Sometimes it works great, then (without touching anything) I can only transmit on one side or the other (pilot / co-pilot jacks), and it will switch back to the other side after starting the plane (sometimes) then switch while in flight. I don't touch anything.

Any ideas?

I'm thinking the intercom is bad.

Well, we can chaulk this one up to operator error.

The PPT buttons are located on the throttle and I was alternating back and forth between the throttle for the co-pilot & pilot. The intercom & radio works just fine.