Here's another interesting twist on this problem. The last time I was able to use SDC, it installed an update to itself without asking whether or not I wanted an update; it downloaded and installed the update immediately upon opening SDC. And that's the last time I could open it, regardless of whether I used my ObjectDock shortcut, the one on the Start Menu, or going to the Stardock folder itself and trying to load it directly.
Each time, it asks me to use "loader.exe." There is no such file on any of my hard drives. The backups I made of the Stardock folder and each of my user folders (using Retrospect; I have a workaround to allow it to backup hidden and system files) to a different (external) drive don't have that program in them. The Stardock Folder in Common Files doesn't have it right now, nor do any of my User folders; there's no such file anywhere. A System Restore point set a couple of hours before that drive-by update doesn't have it. I can't use Stardock's own restore files or utilities, because they all ask for loader.exe. I also can't uninstall any/all of Stardock's products so I can start all over, because they all want loader.exe. I can't ask Stardock for help, since I can't remember my password for support, their computer says my email address is not on record (an error on their computer that handles registration, I suspect), and when I click on their Forgot my Information link, it says that the info is on the way (to my correct email address, which the applet just said was not registered), but it never actually comes. I've also tried directly emailing Stardock Support, but the email gets kicked back.
I suppose I could manually delete Stardock file on my hard drive, and then hunt down every registry entry relating to Stardock or any of its products, but that's very tedious, time consuming, and any kind of registry surgery is potentially dangerous. I could restore the Stardock files from my backups, but that could also confuse the registry and I consider it a last resort.
I'm hoping that someone with Stardock happens upon this entry and can solve the problem. My subscription isn't even near the renewal time, so I think I deserve some help from Stardock.