I have chosen not to replace explorer with diropus. But when I click on the Windows Explorer icon on the start-bar, diropus pops up. It's ONLY there this happen. I haven't found any way to fix that.
Which versions of Opus (9.5?) and Windows 7? (RTM? 32 or 64 bit?)
Did you ever install a version of Opus on the machine before Opus 9.5?
Which folder opens when you click the Explroer icon? Does the same happen if you run Explorer via the Start Menu instead of the taskbar?
If you made the Explorer Replacement choice during the install, could you open Settings -> Preferences / Launching Opus / Explorer Replacement and confirm it is set to "Don't replace Explorer" as expected? (It might also be worth a try to set it to something else, apply that, then set it back to not replacing, and apply again.)
The problem may also be solved by manually removing the Explorer Replacement settings, though you shouldn't normally have to do that.
Another thing to check is that Opus isn't running with any compatibility settings turned on, as that will cause problems with Explorer Replacement. To check that, dopus.exe under program files, right-click it and open the Properties dialog. On the Compatibility tab make sure none of the options are turned on. (That includes the Run as Administrator option, which needs to be off like all the others.) Do the same for dopusrt.exe and (if you're on 64-bit Windows) dopusx64.exe. If any compatibility flags were on, clear them, OK the Properties window, then reboot.
I was using 9.1 64-bit with W7 RC. It didn't have the "Replace explorer" choice by some strange reason. Upgraded now to 9.5 and there it was! And it stod on "Replace explorer". So now it's fixed.
Didn't 9.1 have that menu-choice or was it my windows who bugged?
Explorer Replacement was disabled in Windows 7 until 9.5 when it was properly supported.