> the installation program that needs to be run is called "setup.exe" on the root directory of the USB drive

That was the final key to the mystery, thank you!
The mannual says it is usually in C:\bb\ but this is not true. It is in the root.

So far the external USB drive is mounting to F: every time.

Everything seems to be working fine as long as I don't select Microsoft GS Wavetable Synth.