I've found a fix when you can't upload a course to your garmin device (via laptop / usb) because of Courses (Transfer Error). Go on to the garmin connect (website). Go to your device (right hand side of website) and delete the item from the sync queue. The item will appear where I have highlighted red on the screen shot!
Frustrated me for days until I found a fix so just sharing :) ciq.forums.garmin.com/.../1276064.png
