Apple Logic Pro /LogicExpress Discussion

Hey, I've been having an intermittent problem with audio.  I'm running a single instrument (Kontakt 4 player), and occasionally, I get a click sound accompanied by my meters topping out on my output and no sound coming out.   It's not consistent enough for me to isolate where the problem is coming from, so am wondering if anyone else has experienced this.  The problem sequence is:

1.  Loud click sound
2.  Output meters max out at 6dB and stay there until I Option-Click on the inserts
3.  From the moment the meters max out, there is no more sound from any audio channels, whether the meters return to normal or not.  I have to quit Logic and restart to get sound again.

There are many potential sources of the problem.  Here is my chain:

1. Kontakt 4 playing Akoustik Piano
2. UAD Precision Buss Compressor plug
3. BBE Sonic Maximizer plug
4. MOTU 828 (original) firewire interface

If anyone has an idea where I can look to fix this, I would appreciate it.  

Thanks,

Gregory