Maybe sound [censored], but it was so long ago since i played Fallout 3 so i have forgot it.

What does the "greyed" out quest point means? I can't reach it so i guess it's under ground or something.

The screenshot is taken in Primm

http://img30.imageshack.us/img30/9967/l908.jpg

I believe it is a secondary checkpoint, for something optional as part of a quest you have listed. That, or a marker you placed yourself that you have yet to reach.

It took me a couple minutes, but I figured it out.

In New Vegas, you have the ability to set a personal waypoint on your world map by right-clicking. That waypoint appears as an "empty" quest marker, both on the world map and when you're standing before it.

I was going to have this awesome thing with screenshots illustrating it, since I found out New Vegas had a waypoint ability about ten minutes ago while investigating this, but then I just didn't.

Thanks. That explains it

Just right click and remove waypoint did it.