Since downloading Opera on Windows 10 I've noticed a persistently weird behaviour - when it crashes the MOZILLA FIREFOX crash reporter opens up, instead, though both Opera and the Opera crash reporter show up in the Task Manager as still open (just not on screen).

Firefox was not running at the time, not even as a program listed in the Task Manager but not on-screen, either.

Any idea what's causing this?

It's not affecting my use of either browser. It's just really strange.