You install the Home program ON THE COMPUTER, not the unit.
The application goes on the unit, either internal or a sdhc card, but normally the former.
1. Get the latest Home application from tomtom.com/home and install on the computer.
2. Connect your unit with the card inserted to the computer. Now, use Explorer, not Home and see if you can see the contents of the unit as a drive on the computer. If so, delete all loose files in the root of the unit, NO folders or their contents. Delete any loose files on the sdhc card, again NO folders.
3. Connect to Home. See if an application is offered. If so, install and disconnect PROPERLY from Home using the Device Disconnect icon