I had the same problem, now have VCDS Lite working perfectly... Can't entirely remember what I did but this sounds somewhat familiar
"Go into system settings ,device manager then select ports right click on your usb serial port, select properties then port settings, select advanced you should then be able to choose a new port for your device.
You will also see the latency setting on the screen if you test the lead and it shows the latency as poor you will need to reduce this from 16ms for better results"
I remember I changed the com port and one of the settings as I had the latency issues but cant find the exact page, i'll have another look though.