OK now this is entirely screwed up. Mixed results now...
I pulled the OS 3,9 FastFileSystem off of the 3.9 CD and dropped it in place of the 43.20 version had in L: on my 3.1 install. I then set the thimb drive to use it in HDInstTools, and started formatting. Each partition formatted w/o issue except it froze on the last one about 95% in.
So I rebooted and found that the FastFileSystem I had assigned to the drive was gone because I forgot to save the settings. I set it again and started formatting again from scratch to ensure the FastFileSystem was being taken into account, and the computer GURU'd within a minute.
Frustrated, I turned it off and left it for a while - about 1 1/2 hours. Then I went back to it.
I booted her up, verified the FFS was still associated to it, and then started formatting. Each partition formatted w/o issue.
So now my mid is wondering if it's something with the flah, something with the A3K, something with the DENEB, something with a driver, etc. So frustrating.