Dimming on factory NAV with 'auto' light function...

[seventwozero]

I normally leave the headlights on the 'auto' function, today while driving home from work the display on my 04's factory NAV unit goes really dark, not quite off but pretty close. Thinking the worst I start trying my options, I turn the lighting nob to parking and the display comes back, same with the headlights so I now know the display actually still works. Is there some sort of fuse or relay that may have blown causing the auto dimming on the nav unit to not work with the auto dimming on the headlights?

To be a little more clear, with the 'auto' headlight function selected, the nav unit is dark when the DRL's are on but lights to its normal brightness with parking lights or headlights.