Hi Galen Weston,
sorry to hear about your problems. Let's go through them step-by-step, to make sure I understand you correctly.
First of all - I still don't know exactly whether you're talking about Vienna MIR Pro used as part of Vienna Ensemble Pro, or the plug-in version of MIR Pro. I assume it's the latter.
Furthermore, please tell us what OS-version you're using (you wrote that you're using a Windows-system as well as a Mac), and whether it's 32 bit or 64bit. Knowing your audio system could help, too.
I have the latest Mac Pro with 32 gigs of ram and a very fast PC with 64 gigs of ram (all SSD drives) and DS string with Orchestral Violas, Cellos and Bass can not really run with Mir Pro with the midi tracks. Galen
If the problem persists, please send a mail to to make sure that the issue gets the full attention of VSL's support team (the forum is mainly meant as a communication platform, not as an official technical support channel).
Kind regards,
/Dietz - Vienna Symphonic Library