[ The thread More of the same - Vista + DO9 issues moved into the same topic as this one so we've locked the other thread and will continue here to try to keep all the info in one place. ]
Quad, what you described in the other thread, about dopusrt.exe being blocked at startup and not being able to send messages to dopus.exe, sounds precisely like what will happen if one of dopusrt.exe and dopus.exe are running as administrator.
I know you uninstalled Opus and did a fresh install but it's possible Windows remembers the "administrator" state separately (I don't know to be honest). Could you check the properties for both dopusrt.exe and dopus.exe to make sure they're not set to run as administrator (or any other compatibility settings)?
Regarding the Opus 8 icon on your desktop, a few people over in this thread had problems with Windows caching the old Opus 8 icon. They solved it by using TweakUI to clear and rebuild their icon caches. Seems that Windows isn't noticing that the icon file has changed for some people.