Actually, the paths database is either corrupt, or inaccessible. That's not located in the normally user accessible area. I know because I was futzing with it not long back. If the folder doesn't exist, MM can just recreate it and a default paths db.

You should find it by going to "/home/user/.maemo-mapper/" If you can't get into that folder, you'll need to do it either from the console, or from something like emelFM2. If that path exists, and the folder exists, and the file exists, delete the .maemo-mapper folder and the file inside, then reopen MM. It should rebuild everything by default.

Also, be sure that you have enough spare room on your main drive. Lack of that can cause the db to be improperly generated and thus broken. As YoDude said, make sure that your maps directory isn't on your main drive, but rather either your mmc2 or your external card which is mmc1. I prefer the last one. Especially since my database has now crossed the 4gb line and should continue growing till it hits nearly 6gb. heh.