Does the crash only happen with certain files, or file paths? e.g. Are paths with only ASCII/English characters OK or does it affect them as well? (They should both work, but it's worth checking in case it is related.)
Was the same file used to test in Explorer, or a different one?
If possible, please try with any anti-virus scanner disabled, in case it is causing problems. (It may trust Explorer more than it trusts Opus when it comes to embedding other programs, for example.)
Use a trusted document and turn anti-virus back on after testing, of course.
What do you see if you configure this plugin? Please post a screenshot of the configuration dialog (2nd image below).