CC thinks I have an app installed that I don't

Windows 7, 64.

The CC app shows Acrobat DC as installed on my system, even though it isn't. It's been uninstalled.

(I have verified that it is not on my system).

The CC app button shows 'update' as you might expect for an installed app.

If I request uninstall from the 'gear' menu the 'uninstalling Acrobat...' message pops up for about a second - showing '0%' completion - then disappears. That's it.

Acrobat is still left showing as installed.

Hitting the update button leads to a message : "Acrobat can't be updated... please uninstall the existing version of Acrobat"

What fun... : (

Any suggestions?

Ultimately I would like Acrobat CC 2105 re-installed....