I'm running Pro Tools 7.4.2 on OS X Leopard 10.5.4, and I've had intermittent issues with recording. I recorded a song that had several tracks without incident, but now, if I record-enable a track, it displays a clipped level and records a flat, silent track. It seems unrelated to the interface (mbox), this can be connected to the Mac with no ins or outs and it still occurs; if connected the levels sound fine but don't record. I loaded the latest Pro Tools CS update and it worked again for a day, but the problem has recurred. Any ideas?