Q-master frequently crashes when set up for multi core use.

On my Mac Pro running 10.6.8 and FCP 7, compressor fails A LOT when using multiple cores. I have tried using 8, instead of 16. It still crashes. Unless its one very short sequence. Using the default setting always works.

Any Ideas, I have digital Rebellion and I've run it.

How much RAM do you have? Apple recommends 1 GB per Compressor instance but it really depends on the codec. For low-complexity codecs like DV you can probably use every core without penalty but for more complex codecs like H.264 you may need to scale it back.

My software:
Pro Maintenance Tools - Tools to keep Final Cut Studio, Final Cut Pro X, Avid Media Composer and Adobe Premiere Pro running smoothly and fix problems when they arise
Pro Media Tools - Edit QuickTime chapters and metadata, detect gamma shifts, edit markers, watch renders and more
More tools...

Over 20 gigs. And it gives a "host failed" message, converting ProRes hq, into ProRes lt. So I've got something I'm doing wrong.

Do you have a name set for your computer in the Sharing dialog in System Preferences? Not having one can cause issues like this.

Also, are you submitting to This Computer or a cluster?

My software:
Pro Maintenance Tools - Tools to keep Final Cut Studio, Final Cut Pro X, Avid Media Composer and Adobe Premiere Pro running smoothly and fix problems when they arise
Pro Media Tools - Edit QuickTime chapters and metadata, detect gamma shifts, edit markers, watch renders and more
More tools...

Actually, never mind that last one, of course you're submitting to a cluster.

My software:
Pro Maintenance Tools - Tools to keep Final Cut Studio, Final Cut Pro X, Avid Media Composer and Adobe Premiere Pro running smoothly and fix problems when they arise
Pro Media Tools - Edit QuickTime chapters and metadata, detect gamma shifts, edit markers, watch renders and more
More tools...