Well, I thought I'd found the problem, but my fix didn't work.
Initial download was PeridexisErrant's pack, 0.43.05-r06
The launcher wouldn't start, and there were no error messages.
I downloaded PyLNP_0.11_console and copied it to the same location as the pack's launcher file, and the launcher opened, but...
...I couldn't enable DFHack.
Downloaded DFHack 0.43.05-r1, copied it over pack's DFhack files, and then I could enable DFHack.
When I try to run the game from the launcher, I get the error "Image not found. Not found: data/art/mouse.png"
So I checked each graphics set in the LNP. It turns out Spacefox, the set I selected, WAS missing mouse.png. I felt a thrill of imminent victory! I copied the .png from Phoebus to Spacefox and ran PyLNP again... with no luck. Then I remembered I'd have to reinstall the graphics through PyLNP, so I did that, expecting certain success -- and I still get the same error. So THEN I gave up on the slick automatic launcher method, and copied mouse.png straight into dwarf fortress 043.05/data/art, rather than into the equivalent directory in the LNP --
and THAT worked. \o/
WHOOHOO, DWARVES!
As to where I found mention of the error in windows -- turns out I didn't, quite. I got confused in my hunting. A windows bug with missing "data/art/curses_640x300.png" was
reported on the Bay12 Mantis tracker, and it was cross-referenced from the
linux bug report which included both that file and mouse.png. It was also for version 0.34, not 0.43, and for windows XP, rather than 10.