Celemony released an update that crashes Mixcraft 8 and 9. We're got a fix for this in Mixcraft 9 Pro Studio build 469. Choose check for updates from Mixcraft's Help menu, then quit Mixcraft as the patch downloads in order to install it.
Or, log into your Acoustica.com account and download the latest version of MIxcraft from there.
Mixcraft 8 users should revert to an earlier version of Melodyne. You can contact Celemony for help with downgrading: Contact Celemony
If any Mixcraft 8 Pro Studio users want to upgrade to Mixcraft 9 Pro Studio, that's an option, too: Mixcraft Upgrades