About usb100.dll: I don't understand why pulling the stuff from the BWW repo and building yourself works better than what is put in Netlabs. The only thing that Silvan did was to build it, likely with optimization.
Remember the NEW libusb is in Netlabs EXP and not (yet) in Netlabs REL !
Edit: sorry, did not read all postings, you are using the correct DLLs.
Still don't understand. My own built libusb DLL works as good as the one from Netlabs repo. I cannot spot any functional difference.