Werid Sends Behaviour

[tadx]

I got few Return tracks set up with compressors, reverbs and stuff. I send signal to return tracks to beef up bass, drums, add some reverb, etc.
Suddenly in the middle of arrangement some of returns stop recieving any signal, though sends are in the same position.
Sometimes it starts working again after few bars, but still it's enough to piss me off and screw up the track.

Is it some lovely bug, or I'm missing something?




I'm using Live 6.0.10 on Powerbook G4 17" 1.67GHz