Thanks to all (past n future) for your attention to my issue...
login123, you give me hope that I'm not alone in having this problem.
(though I can't imagine we're the only 2, and this issue hasn't been reported 'til now)
DennisD, I did as you suggested and, yay, it worked! Though, boo, of course these MRUs should be independent. As for your affection of a collapsed registry, I hope you can come to accept us who prefer to keep a 'bookmark' in our registries. And, as for your mysterious registry auto-collapse, try Not running CCleaner, running regedit, selecting a key, rebooting, then checking if your registry collapsed. I suspect something else is at work here.
I suspect still that this issue occurs on a small population of users. As I said before, I reverted back to version 3.04.1389 and had the same problem. I can't imagine this problem has existed so long, unreported...
(apparently, I suspect a lot. Must be my medication, I suspect.)
Sooo, what's my next step? login123, I, and likely 10's of us can't sleep until this problem is slain!