Our 2004 Chevy Venture does have (had) daytime running lights and automatic head/tail lights. Now, the head lights/tail lights never turn off, not the DRL, the real head/tail/dash lights stay on whenever the van is running. Any thoughts on the most likely parts in the system to start with for troubleshooting?

 

and now the headlights went back to working correctly all on their own...go figure...

 

Urm... did you by by chance lay your newspaper on the dash and forget to take it back off, accidentally covering the light sensor which turns the headlights on?
I know that sounds silly, but even simpler was a moth that was laying on top of mine for a couple of weeks, drove me nuts figuring out why the lights were wigging out like that.
Hope your problem is gone for good! Problems with mine are endless it seems.