Ray, can you make an Explorer, not Home backup of your unit's contents. If not sure how, see here:
https://www.tomtomforums.com/t17864-how-backup-contents-your-unit-computer.html
Then, connect the unit to Home and go to Manage my Device (second tab, purple folder), Device tab, and select to remove the application from the device. You'll get a warning but do it anyway (you HAVE made the Explorer backup by now, right)?
Now, in Home, Update my Unit and you will be offered an application update. In fact, if, under more information, it does NOT say 9.400, then you'll need to install what's offered, disconnect properly from Home using the Device Disconnect icon, reconnect and update again till the newest (as of two days ago) 9.400 application is offered.
Install and disconnect properly.
And, another measure to take .............
After all the above, connect to the computer and download and run three times the ClearFlash application from here:
http://us.support.tomtom.com/app/answers/detail/a_id/6211/kw/clear%20flash
The act of installing it actually causes it to run. As I said, do it three times. It will cause no harm and may help the situation.....
See if the unit acts up now.