That may or may not be related to what you're seeing with Opus. If Avast blocked it or if it wasn't actually run then your system may be OK, but I can't advise on that; you'd have to ask Avast.
Regarding Opus, you can check if the installer or exe/dll files are corrupted, which would be my next step.
You may also want to try the full uninstall/reinstall:
[ul][li]Backup your config first[/li]
[li]Uninstall via the usual place for your version of Windows (look for "GPSoftware Directory Opus" in the list of programs).[/li]
[li]Reboot when prompted at the end.[/li]
[li]After rebooting, make sure no C:\Program Files\GPSoftware directory remains, and delete anything left over if it is still there. There should not be anything left after the reboot, unless there are files you've put in the folder yourself; if there are any, they should be removed.[/li]
[li]Then run the installer, install your licence/certificate, and finally (optionally) reinstall your config.[/li][/ul]
You can use Lost Registration Retrieval to get your certificate file. You may want to do that to ensure you are using the correct and latest version of your certificate, and not an old or expired evaluation cert.