I found out that if you get the following error when trying to request a free trial, it is because

Wayfinder's network is down.

! Licensing failed
System Error.

! Licensing error
An unknown error (0) has occured.

Now that the wayfinder network is up, you will get this error if you try to change your mac address

and get another free trial evaluation.

! Licensing error
An unknown error (99) has occured.

If you try to delete the navicore folder, you will find this message.

! Licensing error
A memory write error has occured.

To fix all this, reset your n810 but the program will report "Free trial expired ****-**-**. Please

purchase the product."

=)

**EDIT**
For future uses.. forget paying a stupid subscription that will expire.

Instead, use Maemo Mapper
http://wiki.openstreetmap.org/index.php/Maemo_mapper

or try Navit
http://wiki.navit-project.org/index.php/Main_Page

Good Luck