What version do you have?
To find out:
Go to the main menu. From there, click on the "SET" or "SETTINGS" selection.
The type of your nav computer and OS will appear on the upper right corner of the screen.
The first digit tells you which version of the nav computer you have, and the last two digits tell you the OS version.
If the first digit is a "4," you have a MK4 computer. If you have a MK4, then the newest OS version is 4-1/00.
Here is a link to the latest version of the OS.
http://tinyurl.com/v31-nav-OS
For others;
If you have a MK3 then use the correct version for your type of nav computer, using the wrong one will damage your MK3
Once you have downloaded the file, unzip it (using winzip or similar) into a sub-dir on your pc.
Then use imgburn or similar (
http://www.imgburn.com/index.php?act=download) to burn a new
(blank) cd with the new downloaded firmware image.
Unzip imgburn, then v31 image and then open imgburn, and select the "write image file to disc" then select the v31 .mds (i think) file.
Select the
Slowest write speed for that disc
(you must do this) and then burn on a good quality cd.
When its finished writing your new firmware cd,
Goto the car open the drivers door,
Goto the nav computer and press eject on drive,
Eject the map disc,
Switch ign to pos 1, leave door open.
Insert firmware disc into drive, follow instruction on nav screen.
Wait (approx 6 mins) till sat nav asks to eject cd and reboot.
Eject cd,
Confirm reboot.
That's it.
Do not switch off ignition or close the door when doing the upgrade.
As you are doing the OS update, you may as well look at modding the splash screen, sky and pointers.
This is what I have.
http://tinyurl.com/My-bits
My modded version of v31, with mods already done.
http://tinyurl.com/My-Modded-v31
Hope this helps.
Note; All of the above done at your own risk.