Have installed what I believe to be all the latest software - License control center, ViennaInstrumentsSoftwareOSX-1.12 and ViennaEnsembleSoftwareOSX-2.0-beta3
A quick check reveals that Ensemble starts up fine in standalone mode but when Logic comes to scan newly installed AU units the progress bar gets to the Vienna Ensemble and gets stuck (how long should it take to check it through?). During the period it is trying to scan, the Vienna Ensemble Service (It actually says Vienna Ensemble Server in the title bar) starts up and there is a brief showing of the UI. Logic doesn't even give up on the scan to states that Validation has failed. I have removed the Ensemble component from my Components Library for now and Logic starts OK.
Dual PPC G5 4 gig RAM
OS is 10.4.10
Logic is 7.2.3 How can you tell I am running VI 1.12 as in LOGIC AU listing it is classed as 1.0 - Ah Found it: Open up the Component with control click/ show package contents and read the text in the Info.plist