Perhaps this has been covered (no good results on the search).
Is there ANY way (I'm not afraid of Task Manager 
) that we can install new versions of Opus without a reboot at the end? I've closed the existing install, killed any tasks that look related ...
Surely there has to be a way to install without a reboot. Thoughts?
If you do not have the Desktop Double-Click option turned on then you can probably avoid a reboot by killing all copies of explorer.exe, installing, then starting explorer.exe again. That's because Explorer locks dopuslib.dll for the shell extension, and Explorer (annoyingly!) provides no way to ask it to release a shell extension.
However, if Desktop Double-Click is turned on (which is likely as it's really nice ) then you'll probably find lots and lots of other processes have dopuslib.dll locked. This happens because Opus installs a hook to detect the double-click and, unfortunately, that hook results in dopuslib.dll being loaded into just about everything.
This is also why you don't need to reboot the first time you install Opus, only when you upgrade (because, one way or another, dopuslib.dll is usually in use and cannot be overwritten).
Edit (years later): You may also run into problems if you enable Explorer Replacement and don't reboot after updating Opus.
Here is one very unofficial idea, though:
Exit Opus, then rename all of the DLLs in the main Opus folder and the Languages sub-folder to something else (*_old or whatever), then kill explorer.exe and install the new version. You probably won't be asked to reboot. (This takes advantage of the fact that you can rename a DLL even when it's in-use.)
Take note though! If you notice any instability or bugs then you should reboot after installing this way in case problems are caused by different versions of dopuslib.dll being in memory at the same time. The old, renamed dopuslib.dll will still be loaded into multiple programs. It's usually harmless but it's not completely without risk.
Very interesting. Thanks!
Figured I'd post my findings ...
Alright ... the apparent key to installing an upgrade of Dopus over an old one without a restart is this;
This sounds like a HUGE pain in the arse, but believe me - once you've done it a time or two, it's MUCH faster than waiting for the reboot and you don't have to close everything you're doing to do it (closing explorer doesn't close apps running).
If you get prompted for a reboot and then start Opus anyway without rebooting then you will run into problems eventually. Most likely dopuslib.dll was locked and you're not running a new version with an old DLL. Sometimes you can get away with it; sometimes you can't.
If none of Opus's files were locked during installation then you won't be prompted to reboot at all. That's the sign of a clean, reboot-free installation.
Renaming the DLLs before you start the install is usually safe.
You can use my ListPFRO tool to see which files are scheduled to be overwritten the next time you reboot. I bet dopuslib.dll is one of them.
Also, you can exit dopusrt.exe cleanly by running "dopusrt.exe /dblclk=off", though I doubt there's any danger in killing it via task manager as I don't think it stores any data.
Thanks for the added info! Dopus did report the proper version number when I checked it after the install, but I doubt that matters in this case.