

Neither of these actions 'fixed' the problem of it finding evidence of a ghost Opera somewhere in my system files. Following the further advice I received from you, I did two sequential uninstall/installs of CCleaner - first with the slim version and second with the normal installer. This has been an intriguing experiment with a bizarre consequence. The Pro version (or Pro trial) can even clear up leftovers from things that were uninstalled before you got Revo using a special mode, again read up about it before trying. Revo will use Operas own uninstaller and then search for leftovers, if you tell it to, again be careful and use with care (you don't want to remove the wrong thing). If you get the Free version of Revo then the easiest way is probably to reinstall Opera and then uninstall it again using Revo.

Revo uninstaller is good at finding those leftovers and removing them, use with care and read up about using it before trying. (or you could reinstall Windows, but that's a bit drastic for a minor annoyance).

If you are on Windows 10 you could ignore it until the next Windows Feature Update which should (may) remove the ghost. If you are confident using the Registry Editor then you could search it for anything 'Opera' - Usual warning: Don't use the Registry Editor if you are not confident in doing so, you could mess or even brick your machine if you are not sure what you are doing in there. if you had/havea certain file type set to open in Opera then there will be a reg entry for that.

It's probably a registry key, possibly a file association somewhere - ie. (Some do it deliberately, so that if for instance you try to install more than one free trial they will know you've already had one). Many apps when uninstalled will leave traces behind. There will be a leftover from the Opera uninstall still lingering somewhere on your computer which CCleaner is still finding.
