well i had big big problems am using 409.1 and cheap ebay cable and if u have already installed the cable once before not worked you have
problem did same as me and messed up all com ports in dervice manager, what i did was restore windows before i installed then reinstalled 409.1 after that installed cable with the ross tech driver witch come on a disc and was exact same!
picked it up as high speed (something) converter after that went to dervise manager and went to coms and lpd! after that set it to port 1,2,3,4 thats not in used, open vagcom(409.1) options then selected port i choose in dervise manager after that saved and taken it to car once plugged into car i clicked tested then it said found interface(the car) then vagcom worked fine but kept freezing up after that i Restarted and works a dream now hope this helps!!