So, Trevor gives me his camera and the marker just fine. And I go out to the map marker. And I fine the lethe wyvern just fine. And I get a picture. And, just because I can, I preemptively self defense it to death. But when I turn the picture in, the game freezes right after "I got it, I got it!" gets clicked. Am I doing something wrong? Is this just a bug I can fix easily? Am I explicitly supposed to *not* kill it?
Went and redid it without killing it, same problem. So, nevermind on that.

Whatever's causing this, it's definitely a bug. I've done that quest dozens of times, both with and without killing the beast, and the game has never crashed on me there.

So, first question: what version of the game are you using? Have you installed the UAP (the unofficial patch), and if so, which version? (The patch is highly recommended, because it fixes a ton of bugs; but it also changes the gameplay somewhat from the vanilla version, and isn't backwards compatible. Which basically means that you probably shouldn't continue to play any saved games that you started before installing or updating the patch.)

Next question: what kind of computer are you running it on, and which operating system? Are you running any background programs or apps that might be conflicting with Arcanum? Are you trying to run it in windowed mode? Do you have the hi-res town maps installed? (This last one is generally a bad idea, since it seems to be responsible for more crashes and other problems than everything else combined.)

So, funny story there. I think I was running on an old, basic UAP because I noticed the one in the thread from last month. So I updated to that. And I selected All The Mods. Since I was using a custom background, it overwrote my background. So now my elf is a mountain troll. I'm um... Going to start a new game and futz around.

The most current patch is v2.0.2; it should say that on the lower left corner of the Arcanum load screen. If it doesn't, then you can download the latest patch right here.

Again, tho, be sure NOT to install the hi-res town maps; they never seem to work right. In fact, I still recommend a clean re-install, since you've had at least one unknown bug crash your game already.