Using ShellExView (as suggested by Leo elsewhere) it appears that Pushbullet for Windows (v328) is causing a conflict with Directory Opus (11.13.5564 x64).
ShellExView reports the offending file and its location as:
However, the file does not exist and may be a left-over in the Registry which was not eliminated when Pushbullet, at some point, was updated.
I've sent the same message to Pushbullet and asked them to clarify.
That's a .Net DLL.
.Net is not meant to be used to write shell extensions. It will cause various problems due to conflicts with other things wanting to use a different version of .Net in the same host. (Which can include the host itself.)
This may or may not be related to the crash, but suggests the shell extension hasn't been written according to the guidelines. (Which is somewhat understandable, as Microsoft aren't always good at putting them in one place, or outside of blog posts.)