My bud had the same problem, and I found this posted over at the [H]. It fixed his issue, so give it a shot.
1. right click your 2142 icon and go to properties
2. click on the "find target" button
3. in the window that just came up go to Tools -> Folder Options -> View
4. now, find the box that says "show hidden files and folders" click it so it is checked.
Now scroll jsut a litte below that and find the box that says "Hide protected operating system files [recommended], uncheck that box and then hit ok.
5. now find the folder named 'radial.cdb' and re-name it to oradial.cdb
that will fix the problem where the map will stop a little past half-way.
You can delete radial.cdb instead of renaming it if you're not worried about backing up the file.