If you want to, you can reinstall Opus and turn off Explorer Replacement (Preferences / Launching Opus / Explorer Replacement / Don't replace Explorer) so that it not interact with other programs and only opens when you run it explicitly.
If you can't open Preferences the normal way, paste this line into the box at the bottom of the Start Menu and push return:
"C:\Program Files\GPSoftware\Directory Opus\dopusrt.exe" /cmd Prefs PAGE=explorerrepTrying the two things I mentioned before is then worth doing, to see if the problem only happens when opening Opus in a certain way, or when asking Opus to show a certain folder. (Crash, exit or high CPU usage when viewing certain directories covers that.)
If the problem happens for all folders, General slowdown or instability investigation steps has various suggestions which may help. The one I would try first is to make sure you do not have anything pointing to unreachable network drives in you system. That might be a drive letter that has been mapped to a computer which is no longer on the network, or it could be something added to your Opus toolbars which points to a computer that's not on the network. If it's either of those things, then the "not responding" message should last about a minute, rather than forever, which is a good indication it's that type of problem.