@mondul I'm sorry it's been so long since I offered to test it, I was away from my usual workstation and I forgot to copy my NAND to go.
I've just tried the latest version (2.9.9.1) with my NAND dump on an empty FAT32 formatted 2GB micro SD, and I actually still have the same problem. I still seem to be booting to the internal NAND instead of the SD's, and attempting to turn autoboot on results in the black "An error has occurred" screen.
Since the first try didn't involve a fresh format, I re-formatted the SD (with FAT32) and tried the same thing again, only to get the same result...
Oddly enough, I'm not getting any problems with the downloads...