MBP sleeps unexpectedly, black screen shows " z z Z" I've NEVER seen before

Question

I found plenty of posts on Macs NOT sleeping. I have the opposite.
About an hour ago, abruptly my screen went black except for three "Z"s in the middle, stacked lopsidedly. Seems pretty evident that it's put my MBP to sleep. I click the spacebar and return; it takes maybe 10-12 seconds to come back up (usually it's instantly when I hit it that quickly).
I checked my Sleep and Energy Saver settings. As usual: computer NEVER sleep, display sleep at 5 minutes. As it happened several times, I wondered if it were getting that 5-minute interval somehow. I upped it to 15 minutes, and it did "z z z" again, but at something like 17-18 minutes (hadn't noted the seconds), so that seems to rule out it getting some instructions from that preference.
The only plist I recognized as possibly involved: com.apple.preference.desktopscreeneffect.plist
Made no difference. It happened again just a few minutes after I moved that to the desktop. Does anyone have any ideas about some other plist to which this may relate?
I can't find ANYTHING online reporting this. And as a Machead since 1986, I don't recall ever seeing this kind of sudden sleep.
Recent installs: a week or two ago I did install a "Fireflies" screen saver, which is basically a more lively variation on Apple's "Flurry." I used it for a few days, no problem, then went back to something else. I did start it up again last night, but I had no problem then.
Still troubleshooting, I've changed my Energy Saver to "Never" for both computer and screen. As I'm typing this, the last "Z Z Z" happened over a half-hour ago.
And WHOA — for just a moment, right then, I saw a probably briefest-possible black screen — but it didn't continue to the "z z z."
Has anyone ever seen this happen? Any other plists or apps to suggest?
Thanks,
Chuck B

Answer 1

Björn Herrmann wrote:
...If you do not pair your Mac with one remote it will react to all of them. So you can use it with several Macs within reach and they will react all at once. -> Fun at the workplace.
Heh, you read my mind on this. When I first started using Keynote I did deliberately pair it for only my MacBook, to PREVENT problems. Now I may undo that, because I can think of a few people with whom I might play around a little — who wouldn't mind the joke.
Of course, if, unlike me, they already know the remote does that, they'll probably just turn around and say "CUT IT OUT ALREADY."
Obviously you're way ahead of me on Mac stuff, so you probably already know ctrl-opt-cmd-8 as a toggle for reversing the screen colors, another funky little trick.
Danke!
Chuck