IF you did run a registry cleaner to remove remnants of the old a/v's, that is not the proper way to remove.
The proper way is to use Add/Remove, and then use the links for SingularLabs. But, as you did not know about that beforehand, it may be too late. What is done is done.
Revo Uninstaller should never be used to uninstall an antivirus program, for example. Too many problems can result when used for this purpose. It is fine for all other programs except a/v and security solutions. A/V programs run drivers that are deeply embedded in the operating system, unlike other third-party programs an user may install. These drivers help to protect the system from malware damage and infection.
When removed improperly, it can/will cause system damage.
You have not yet posted to Carol's query about Eusing Registry Cleaner, so we need to know if you used it. Then we can answer your question much more directly, as that would/could have a direct bearing on the dialog box/notice you are seeing.
Registry cleaners can/will cause system damage so deep that the only recourse is a clean and fresh re-install of the operating system if the wrong entries recommended by that cleaner are removed/deleted. Changes made by a registry cleaner are permanent unless a registry backup is made just before the operation is done.
Some cleaners provide a way to backup the registry just for this purpose.
One way to undo the damage is to restore all the changes made by the registry cleaner and start over.