Removing stuck screw from inner door panel.

[PoDuck]

Okay, I've had stuck screws before, and usually I can figure out a solution. Usually a few good taps on the end of my impact driver gets them right out, if not, add a little penetrating oil.

Right now though, I have a single screw on my door panel that acts like it has been welded in. If it is rusted, it isn't noticeable from the head. All the rest of the screws came out very easily and have no rust on them. I also had this door panel off a few years back, and I didn't use any kind of glue or anything that would cause it to stick when putting it back in.

I've spent about half an hour trying to get my impact driver to work it out and I get nowhere. It doesn't even budge. What does budge is the metal of the door with the concussion of the impact driver. It has started bending inward, and I'm going to have to work it a little to get it back straight.

Does anyone have good, non-destructive ways to get screws out?