My result here was that running the 'Vienna Ensemble PRO 5 / MIR PRO / MIR PRO 24 (Mac OS X) build 10988' installer made the Vienna Ensemble Pro folder in Applications vanish altogether, complete deletion of the application. and nothing in the trash.
OSX.6.8; the extant installation was 5.0.10683. Is 10738 a prerequisite or is this just botched. and the new VI Pro installer got rid of the VI Pro AU, so there is nothing in VE Pro where that is instantiated. I don't think it's me, unless both files were strangely corrupted. they were the right size and there was no indication during the installation of any problem.
I had no problem reinstalling 10683. or the prev. version of VI Pro archived.
We cannot confirm your findings. All applications install properly. We also haven't had another user report these issues, so I guess this is related to your system. Please send a mail to support@vsl.co.at, so we can investigate this issue further. You can mark the email "to Martin".