The navigation is giving me a headache. I need some HELP !

Right guys i've put the v3 DVD into the cars nav.
Its asked me to save the dvd to the Harddrive or use the dvd temporarily. I saved it to the harddrive.
Now when i want to type in an address to navigate to, I can only put in 4 digits of the postcode, is that normal ?
Ie if i want to put in LE1 5FG, it only allows me to put in LE1 5, then it tells me to select that one option, then from there select the street/house number etc.
Is there no way of putting the full post code in ?
Laslty how do i know that the v3 was installed onto the Harddrive, it looks the bloomin same as V2 to me ?
Also whenever i have an address planned and want to use the media screen, the map screen goes away, even when i press Nav, the map showing the directions goes away.
Am i supposed to use the map button to bring back up my map/direction highlights ?
Cheers guys in advance for your help !!
Raj