Haven't played in a while...I was about to start my first FONV mod, but the GECK isn't able to load anything. It has the caravan pack checked, but the master file is deselected as soon as I try to load. Anybody know the problem here?

What error is it giving you?

It doesn't have an error message of any sort...it just can't seem to load the master file for NV. I'll check it in the list, then select my mod as the active file, and try to load, but nothing happens. Then I go back to the list and the master file is unchecked again.

What version of the GECK are you using your should be using 1.3.

I reinstalled it after getting the bug, but that didn't seem to help. I don't know for sure which version, but I think it would be the most recent. Would it have something to do with updating the game itself, or Steam?

I remember this happening to me. You need the right GECK version. Start the GECK and go into the help menu at the top. Select the "about" option. Youll find version info there.
Im able to load falloutnv.esm on my copy.

http://fallout.gamesas.com/eng/downloads/updates-GECK-fnv-eula.php <------ This should be the right version

Okay, I see now. I had the wrong version after all. Thanks everyone, I'll go fix that.