I have the latest 4.10 f/w version.
When loading a route, I sometimes get this. Could it be related to the expired or missing EPO I posted in a different post?
The Garmins need a GPS lock to do the route calculation. The EPO file lets the unit get that lock faster.
Here's a link to the other post:
It's a bit odd that the Garmins need a GPS lock to do the calculation.
I suspect that it only needs the lock to know whether you are near the start point or not (so it can display, "Do you want to navigate to the start?"). It doesn't really need the lock to do the route calculation.