Hi Jim. My name is***** am sorry that you are having this problem. It would be my pleasure to assist you. Your Garmin Nuvi may only accept the official 2 letter abbreviation for the states. Montana would be MT. Please try that and let me know the results. If that does not resolve the problem, please let me know the model number of your Nuvi.
Here is a link to the official two letter abbreviations of the states:
Please give this a try and let me know how it works for you. If this solves the problem, would you mind taking a moment to rate my service? I'd really appreciate it! Without a rating I am not credited for my answer. If this doesn't solve the problem be sure to let me know so we can continue troubleshooting.
You're welcome. Since that didn't work, we may want to do a factory reset on the device. The problem may due to a software glitch and a factory reset will fix most software issues.
Note: A master reset will erase all favorites1 and will restore your device to the default factory settings. If you would like to back up your favorites to your computer, you can find instructions to do so here.
To perform a master reset on a nuvi 300 series device:
After the nuvi resets, follow the on-screen prompts, and then place your device in an area with a clear view of the sky until it acquires satellites.
Note: A master reset will erase all saved favorites
Please try that and let me know the results.
Here is a link to the user manual for your Garmin Nuvi 350. It may be helpful to you in the future. It is in pdf format and can be saved to your computer for later viewing, or printed out.
If your Garmin Nuvi still does not work correctly after the factory reset, please let me know so I can check for possible updates to the firmware or the software. Thank you!
Do you have the Garmin Express software installed on your computer? If not, please download an dinstall it form thsi link:
After it has been installed and you have rebooted your computer, please connect your Garmin Nuvi to your computer and follow the onscreen instructions to update the software. Please let me know the results.