Not a scoob by the way - an Alhambra (Galaxy)

The interior dash lights have stopped working since i fitted a new stereo, but when you turn the external lights on, the interior lights come on then go off.

Is there something obvious I am missing..?

 

Sounds like you have distubed something in the wiring. Can you disconnect the new headunit and see if it reverts to normal, so as to ensure it's not that causing the prob?

 

I'll give it a whirl - cheers