Windows 7: Screen saver issue - two displays

I'm an oddball, I guess. When the Photos screensaver kicks in on my system, I'd like the primary display to show my photos, and the secondary display to go black. The web is full of queries from people who can't get their screensaver to operate on their second display, but I wish it didn't on mine!

Most of the time in Vista 64 it worked the way I want, but a few times after an update of Windows or NVidia driver I had the problem I'm having now: each photo is SPANNED across the two displays... one part on the primary display, the other part on the secondary display. Not a great way to look at photos.

In Vista the problem just corrected itself magically, I swear. It would go wrong, I couldn't find a solution, but one day I would boot, and the screensaver would be working as I want it again.

Windows 7 from day one has spanned the photos. After running it for a couple of months, I've given up waiting for the magic. Is there anything I can do to make the Photos screen saver show my photos on one display only (preferably the primary) and blacken the other display?

Thanks in advance for any ideas.

Asus NVidia GTX 285, Asus P6 motherboard, two Samsung displays