Enduro 2 Following a course

Hi everybody,

My Enduro2 managed again to ruin my day and it did it succesfully yesterdy and the day before.

I created a course (about 100 km with the bike), I transfered it to the watch and then I wanted to start the route. I started the bike-activity, I activated the course navigation and it just didn't worked. I waited more than 15 min but nothing seemed to happen, the watch was still calculating. It reached hardly about 81% after more than 15 min so I got frustrated and started biking without waiting any longer. From that point on was the watch in a continuosly loop by calculating or recalculating. About one hour later it showed I must make a U Turn and then tryed to guide me home, with hunderts of recalculating despite the fact that I haven't just yet done not even about 20 km from the course. 

Please advice, am I doing anything wrong, or do I really need to let that piece of junk go, because I just have enough with this dissapointment of a gear.

Thank you in advance!