Audio engine overload at random times

Hi all,

I've got a serious problem the last couple of days.

I'm using MainStage3 as a live instrument (Stage Piano -> MIDI-Interface -> MainStage (in comibnation with QLab for instrument changes, Playbacks and Click-Tracks) -> Interface -> PA) in a musical production and things were working fine for about a month.

Since last week I get random messages about the audio engine being overloaded ("could not process all data in given time"), mostly occuring when I don't even play a single note. Yesterday the system nearly went to a full crash because of multiple messages in a short amount of time.

Since I didn't change the setup nor changed the software nor tinkered with the MacBook I'm using, I really am at a loss of clues why that stuff started happening and seems to get worse from day to day.

I'm glad for every idea you might have!