My 03 Navigation system only comes on when it is very hot outside and only when initial start. And where can i get a new disc the one in it is scratched

 

google is not your strong point is it.

http://nissan.navigation.com/product...S/NissanNA/USD

 

The OEM system never worked very well, so of course 14 years later, it's going to be even worse compared to anything new. You might find a working DVD on eBay.

best bet is to install a head unit with nav, use your phone for nav, or install an aftermarket nav system in the cubby.