Years ago I worked with a "wedge" PS2 barcode scanner.  It had an odd property that it HAD to have a real keyboard connected to the "outbound" port of the scanner, even if you weren't going to use it.  (IT  was reallty annoying to have an extra keyboard lying arround when the laptop keyboard worked just fine.)

I was wondering if you did the same thing I did.  Use it on your desktop with a "real" keyboard plugged in, and then use it on the laptop all by itself.  For me, plugging in a real keyboard fixed the issue.