OK followed this, when I downloaded Zadig there was nothing in the drop down menu, i had to select list all devices, now STM32 virtual com port came up and I installed the driver. I am now mining BTC side but my Scrypt side now fails even with the --dual option added to the bat file!!!

Are you sure the comport is right? I also had a DM from someone with the same error, in that case the usb port was faulty. So try a different port as well.
The USB port is fine. The PC is brand new build, The device worked before through the port before I switched this driver
To bring you up to speed, check the link below and read the comments:
http://cryptomining-blog.com/1254-how-to-mine-both-btc-and-ltc-on-gridseed-5-chip-gc3355-asic/