For many years I have been using a different zip-application.
Was curious to see what DO was capable to as far as zip files is concerned.
So I changed fileassociation to DO.
Tools/Preferences/Zip files Integration I also tagged Make Opus the system default handler for ZIP files + apply + okay.
Closed DO, relaunched it, the tag was gone.
Again tagged it, apply/okay/close - same as above, the tag was gone.
When opening a zip file the other app was launched.
[ul][li]Open RegEdit.exe[/li]
[li]Go to HKEY_CLASSES_ROOT \ .zip[/li]
[li]Change the default value from PAZIP to OpusZip[/li][/ul]
I think that's all you'll need to do, though it's something Opus should already be trying to do.
If it changes back to PAZIP, your old program may be "protecting" its associations which you'll need to turn off.
It may also be worth reinstalling Opus over the top of itself. A couple of people have found the zip components get unregistered somehow and that solves it. (Don't uninstall Opus or you'll lose your config; just reinstall over the top.)