acrobat not activated as part of CS4?

Installed and activated CS4 Std, running on Vista Ult x64.

EVERY time I run Acrobat Pro 9.1.0, I get a popup that says:

Adobe Acrobat was installed as part of a suite. To enable Adobe Acrobat, please start another component of this suite (such as Adobe Photoshop).

When I click on the OK button, Acrobat closes down.

Of course, running the Photoshop 'component' (already activated, of course) either before, during, or after Acrobat makes no difference whatsoever.

I don't remember this problem coming up before the recent download and installation of the Acrobat 9.1.0 update... and yes, I *did* reboot the machine to complete the update installation.

Any clues or hints?

Thanks, in advance!

- Bob Elkind