Thanks for your update, it is somewhat reassuring (and also an experience bit of guilty pleasure) that others are having problems and it is now just down to my ineptitude.
I left a message on the Locosys website last evening and received a very helpful reply this morning. They have suggested I download the driver intended for Windows 7 which is not apparent on the Mount Best website, the link to this is -
http://www.locosystech.com/download/driver/PL-2303_DriverInstaller_v130.zip they also say that the Navilink has been updated and the link for this is
I will not be able to try to update as I am away for a week however I will let you knowhow it goes when I return.
It would appear that there are problems with the update, on one of my machines it was the first time that I downloaded the installer so it was not confusion between the old and the new. I also tried to download version 1.3 but this failed and I got the same error message.
Locosys have asked if I fail with the new process to let them know when and where I purchased the unit, it could be that they suspect that there is a batch that will be difficult to update.