I have also just bought a nuvi 310 with v8 maps and have the same problem ie refers to roads by their number instead of name, and it is real annoying. Does anyone know how to fix this? Thanks
Your best bet to fix this problem is to use the Garmin Webupdater software.
The webupdater will update the firmware in your unit and sgould correct the issue that you are experiencing.
Here is a link to the download of the webupdater.
P.S I had the same problem, which was fixed after the firmware update!