We got it fixed. One of the following things worked:
- Deleted AccessVirusTI.kext from [macintosh hd] / [library] / [extensions].
- Deleted all files starting with de.access-music.virus_ti(...) from [macintosh hd] / [users] / [username] / [library].
- Deleted the Virus MIDI driver from [macintosh hd] / [library] / [audio] / [midi drivers].
- Uninstalled the Virus TI software suite, and reinstalled with the Virus in USB update mode (exit button + power cord connect on the Virus).
- Checked that no drivers were blocked by the OS [system preferences] / [security & privacy] / [general].
Point 5. actually explained and fixed some other audio-related problems I was having.
Thanks to Access Music Support and Marc. That was some fast and accurate user support .