If there are crash dumps, please also zip and email them to leo@gpsoft.com.au and I'll see if they reveal which component is crashing, or if it's something in our own code, and if it suggests a way to fix things.
We've identified a problem in our code which will be fixed in the next updates. (12.0.8 beta will most likely be the first version with the fix. When we do a 11.19.1 beta or 11.20 stable for Opus 11 it will also be included in that, but that probably won't be for a while, until we more fixes to roll into the same update.)
Until then, you should be able to prevent the crash by examining and fixing a type of problem in the folders which are triggering the crash. It looks like you have some junctions or symbolic links in those folders which are set up in a way that causes them to infinitely recurse into themselves or each other.
Current versions of Opus already detect most such infinite loops in junctions/symlinks, but we found a type of loop which got through our tests. The new versions will close that hole, but you'll probably still want to fix your junctions/symlinks in case they cause problems with other software. It's likely the junctions/symlinks are not useful (since they can never be resolved to a final target path) and ended up in their current state by accident, as the type of loop is not one you'd be likely to create on purpose.
If you turn off the folder tree in Opus, you may find you can browse the problem folders without issue. If you then turn on the Description column, it will show you the targets that any junctions or symbolic links point to. You can use that to diagnose where things are going wrong. Let me know if you have any questions or trouble finding the problem junctions/symlinks.