People always hitting Cary Grant on the head

    One rule of old-time radio seemed to be that when in doubt, you hit Cary Grant on the head so he either loses his memory and identity or gets them back. I have two such shows. One is a Suspense episode, a drama called "The Black Curtain." The other is a comedy called "I Love You Again." The latter is adapted from a movie. Listening to it, I was quite confused. "Wait! Didn't I hear this already as a drama?"
    So many of my old-time radio shows are movie adaptations, and Cary Grant was of course a huge movie star. So I assumed that both shows must have been Cary Grant movies, and thought again that boy, people sure loved hitting Cary Grant on the head! But a little research showed that there was no such Cary Grant movie. (Unless he got hit on the head in "North by Northwest" and only thought it was mistaken identity.)
    I should have been tipped by the fact that the co-star was Myrna Loy that William Powell starred in the movie version of "I Love You Again." "The Black Curtain" wasn't filmed under that title, but Burgess Meredith starred in the film version (the title of which I forget, but since it isn't available on DVD, it doesn't strike me as the most pressing thing to look up).
    So the answer to the eternal question, "How old Cary Grant?" is clearly, "Old Cary Grant is getting hit on the head on the radio. But not in movies."