USB Barcode Scanner (Adesso) not reading on Mac Mini

My friend bought an inexpensive USB bar-code scanner (Adesso Nuscan 1000U), which they said should work fine in OSX, to use on his Intel Mac Mini, running Leopard 10.5.4.

Model Name: Mac mini
Model Identifier: Macmini2,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 4 MB
Memory: 1 GB
Bus Speed: 667 MHz
Boot ROM Version: MM21.009A.B00
SMC Version: 1.19f0
Serial Number: YM7309F0YL2

After plugging the scanner directly into his computer, it was acknowledged to be an "non-standard" keyboard...

- the "Keyboard Setup Assistant" window popped up, and he hit continue (instead of closing the window)
- "Identifying Your Keyboard" came up, and he had hit "z" on his main keyboard (a mistake, he knows now)
- said scanner will not "print scanned data to screen" as it ought to
- scanner "goes to sleep" after it scans it's first barcode - does not 'wake' until unplugged and re-plugged into Mini. Never does this on other machines.
- scanner works perfectly on three other Macs running Leopard (same version on all four machines), both Intel and G4 based
- I have repeatedly trashed the "com.apple.keyboardtype.plist" file in hopes of re-setting his computer to read this device properly, with no luck - but each time it's trashed and we plug in the scanner it pops up the "Keyboard Setup Assistant" window, which we simply close... like on the other test machines.

I know it's not the scanner itself, as it works fine on all other systems with the same OS. We had simply skipped the "Identifying Your Keyboard" prompts and closed those windows and the device merrily scans barcodes and prints them to any text window - as it should.

Is there a chance that some difference in the Mini hardware would somehow not allow this device to work properly with it? I'm completely stumped. Thanks for any assistance!!

-ant.