I seem to recall that the reason was that Windows XP had a very badly broken CDC class driver so everyone (FTDI and Prolific own this market) ignored CDC and ma

I seem to recall that the reason was that Windows XP had a very badly broken CDC class driver so everyone (FTDI and Prolific own this market) ignored CDC and made their interfaces vendor specific. Here's the old knowledge base article for the fix that eventually patched usbser.sys: https://support.microsoft.com/en-ca/kb/943198 https://support.microsoft.com/en-ca/kb/943198