I could've sworn I saw a freebie here that deletes all lights and restores default P5 lights, but I can't find it. Does anyone know where I could find this?

Nope, but you could do the following: Save your own preferences and add them to a UI dot. Restore factory settings, then save the light set out to the Lights library. Restore your own preferences from the UI dot.

I kind of figured I should try just saving the default light set before posting this. :D I wasn't aware that loading the default lights would delete all the existing lights, although I knew it was a possibility. I'm curious though, why would I need to do all the rest? Can't I just open Poser, save the lights, and use that set whenever I want to return to default lighting?

Hmmm, I guess not. Okay, I'll try it your way.

Okay, I have the Light Panel script (Ockham I think), so I just delete all lights then use my saved default lights. That seemed to work okay.

The reason I suggested all of the above was in case you used a heavily customised Poser workspace with a weird light setup. That way, you wouldn't lose your own settings when you revert to factory settings. Glad you got the light set, anyhow.

Naw, I'm a light noob. I've only played with the lights a bit, the only time I use complex lighting, it's canned - someone else's setup I downloaded.

The Light Setter has an option to delete all lights. The Light Panel (the one previously recommended) does not.