Can't get remote cluster machine to encode video - getting 'Media Server application unexpectedly quit'

Question

Hi
Using Compressor 4 / Apple QuarterMaster admin etc, I have set up a Cluster and it works well to Share > Export Using Compressor Settings.  That took some doing, and I'm happy that it works.
If I do all my processing in the foreground, or alternatively in the background on my FCPX computer, ie without running or using any cluster in the background, it all goes well.  Quick, error free. 
If I activate the cluster and only put my local machine's compressor services into it, and then send my compressor batch to the cluster, it works perfectly well.  But that defeats the point of having a cluster.  I want the remote machine to do all the work so my local machine doesn't slow down.
Unfortunately, if I add the remote machine's services into the cluster, the encoding always fails with 'Media Server application unexpectedly quit' in the error log.  I know that the cluster is distributing segments of the file to the remote machine - this can be seen in the Share Monitor, but they never get processed and sit there waiting until I get the error message.
The remote machine is a modern 4G core 2 duo MacBook. It's never been used for this before.  It has Compressor 4 and the Pro Apps Update installed and both appear to work.  Both machines are running 10.6.8.  The remote machine has Compressor services initialised in Apple QMaster sharing.  The QMasterAdmin sees these services.  They are accessible over Bonjour and appear in the Cluster.  Compressor services from both the local and the remote machine are configured exactly the same way.  The same QT codecs exist on both machines.  I've restarted, shift-restarted, etc etc.
So I am at a loss here.  The remote machine just won't compress anything it is sent. 
Any ideas?  Must both have FCPX installed?
Anyone actually got a remote machine in a cluster to work with Compressor 4?  I can't figure it out.
Chris.

Answer 1

OK... finally sorted it out.
It's a bug, as far as I can tell. 
Any job entered directly into Compressor 4 in the normal Compressor manner will be successfully rendered by any working cluster from any machine that can access the cluster.  That's good.  It means that the underlying distributed processing model works well.
HOWEVER - any job forwarded to a Compressor 4 cluster that includes non-local compressor services (ie compressor services not resident on the same machine), using Share > Export Using Compressor Settings direct from FCPX will fail.
To confirm this bug, I made a cluster on a remote machine.  It was a dual core machine, so I enabled 2 compressor services on that machine, and that's all the cluster was.  Simple.
I then manually entered a video file (ProRess 422 720p) into Compressor on the remote machine.  I did this by physically setting up new job using the compressor user interface.  A bog standard ProRes422 720p file rendered fine this way on the remote machine.  As did anything else I gave it.  Good.
Then on my main machine, I opened Compressor and made a job based on the same file and settings, and sent it to the remote machine's cluster.  No problem at all!  Great!
So now I know that both Compressor versions, and the clustering model, are working fine.  In fact I can send all sorts of files to the cluster, from any other version of compressor, and have them processed on the remote machine, and get the result back on my desktop later on.  Excellent.
But, if I try put this same file into a FMPX timeline, and go Share > Export Using Compressor Settings.... and select a cluster with remote (non-local) compressor services, it does not work.  Rendering the video segments on the remote machine times out and fails, every time.  It doesn't matter what file format I use, it just fails. 
So it's a bug. 
From what I can tell, Final Cut Pro X somehow messes up the Share > Export Using Compressor settings where the cluster includes non-local compressor services, causing all jobs to fail.  The same Share > Export Using Compressor Settings will work quite happily if all the services on the cluster are on the same machine as FCPX, or if the job is sent to This Computer in the background.  But any attempt to send files to a cluster using any remote services will fail.
I hope this saves some people from wasting as much time as I have!
One workaround is to export to ProRes then put this file manually into Compressor, sending the job to the remote cluster.  This is a two step process with a large intermediary ProRes file.  If one goes Export as QuickTime movie, generating the intermediary file prevents further FCPX work being done. 
To get the intermediary in the background one could use  Share > Export Using Compressor Settings via either This Computer, or to a cluster using only local services.  Then once complete, manually add it to a compressor job.
So this is a FCPX bug as far as I can tell.
Chris.