Hello orgatrain,
Thanks for the update. We don't actually officially support Hauptwerk v4 any longer (and it isn't fully compatible with recent macOS versions), but perhaps the following may help:
I would suspect a lack of USB power to the relevant port, or macOS is putting something to sleep as a power-saving measure, or perhaps an erratic conflict with some other USB device or driver, or an incompatibility with some macOS update.
To confirm:
1. Are all available macOS updates are applied?
2. Did you download and (re-)install the version of the driver from that link?
3. Do you have the Hauptwerk v4 dongle attached to a USB port directly on your iMac (not via a hub)?
4. Are all other USB devices disconnected, except for the Hauptwerk v4 dongle and any devices that you specifically need for running Hauptwerk (e.g. audio/MIDI interface, mouse, keyboard)? E.g. make sure that no other dongles, and no USB hubs, are connected to the Mac.
5. If you then reboot and try it again, do you still get the error?
6. How about if you exit Hauptwerk, move the dongle to a different USB port on the iMac (not via a USB hub), reboot, then re-launch Hauptwerk? (Perhaps there was some problem with that particular USB port on the Mac.)
7. If so, how about if you try disabling macOS' 'App Nap' globally (see:
https://osxdaily.com/2014/05/13/disable ... -mac-os-x/ ), reboot, then try again?
If you then still have the problem:
- What version of macOS are you running?
- Do you mean that you're having the problem when trying to load the standard Milan Digital Audio Notre Dame de Metz organ? Or a composite organ definition that uses its samples? Or some other organ?
- Has the problem started happening recently, or have you always had the same problem with that organ? If the latter, has any hardware changed, or drivers been changed, or macOS updates applies, since it was last working?
- Are you using Hauptwerk v4.2.1, or are you using an earlier v4 version?
Best regards, Martin.
Hauptwerk software designer/developer, Milan Digital Audio.