Missing folder icons

The problem is most likely an icon/overlay shell extension installed by something which is crashing when called by Opus. For some reason, several cloud storage apps have been doing this recently, at least some versions of them, but there are other types of app which may also be involved.

The ShellExView tool will let you see, and try disabling, the extensions your system has installed.

Please try running ShellExView, then sort its list by Type, and scroll down to the Icon Handler and Icon Overlay Handler entries. Right-click them and tell ShellExView to disable them.

Then, fully exit Opus (e.g. via File -> Exit Directory Opus; closing all the windows is not enough) and re-launch Opus to see if the problem is still there.

If that doesn't help, you can re-enable them in the same way. But if it does help, try re-enabling a few at a time until the problem comes back, narrowing it down until you find the one which seems to be triggering the problem.