07 d7 Headlight and gauges cutting out.

At what RPM's does it do this?
I had the same problem with mine but the idle RPM was too low when the engine was warm so it dropped under 900rpm's, and then the gauge and head light cut for me too.
You could also check the adjuster on the throttle cable located just above the console, this has a tendency to screw itself down causing the throttle cable to get loose and thereby adjust the idle speed down.
If you got like 1300-1330 rpm and it still cut I'd check the VR if I where you, it's a common problem on these.

It's a place to start your search at least

when my headlight dimmed, and gauge quit qorking it was a wire grounding out under the handlegrip for the warmer. my gauge didnt work at all tho untill i pulled the wire out and taped it up. sounds a little different than your issue but maybe somehting to look at??