This is hard to explain in writing, but...
After discovering the various problems with the original XP build I completed a fresh build and rolled it out to Lab B, but the build had various problems. They mostly appear to surround the corruption or mismatching of stored SIDs. Target machines, created from a perfectly functional master, boot to a blank screen with a cursor and nothing else (but only when login is a user that once existed on the master). Ctrl+Alt+Del does nothing, you need to do a hard reboot. Logging in as admin creates a new profile from Default User instead of from admin, and calls it, for example, "admin.Lab-B-02".
I'm sure there's an answer, but I've spent all day on this and have not been successful. So I gave up.
My "solution" is to take the original XP build (the one that first exhibited the USB thumbdrive issue) and update it with the new driver and various other needed adjustments - mostly to do with the general user setup and temp directories. I came in at 5:30 tonight and finished the adjustments, pulled an image, and pushed it out to the machine at my bench (good speed achieved at this hour - 205MB/min).