As a player, there are a few things you can do to troubleshoot this on your own before posting here or elsewhere.
What was the party doing?
First of all, what was the party doing before it happened? If everybody was just walking along, minding their own business, chances are good that it could be a hardware issue, possibly overheating.
What else was running?
Another thing to consider is what you were doing, as a player, when it happened. Overcommitment of CPU capacity is another culprit. If you've got your antivirus running while you're playing, and carrying on a few IM conversations, and shopping for holiday gifts, and writing your thesis, balancing your checkbook, and modifying a portrait, you might want to think about closing a couple applications before restarting the game from your last save.
How big is your installation?
Size matters. If your override folder is enormous, like >1GB, that can contribute to overall lag, where the clock is making jerky movements, everybody is moving across the screen by jumps, if they move at all, and commands are not always acknowledged. It can also contribute to random CTDs. There, it's a judgment call. Do you really need all those NPC mods *right now?* Uninstalling those you don't plan to play immediately will help a great deal, since the WAV files add the most bulk.
Do you come here often?
Was this a one-time CTD, or is this something that happens every time, at the same place? If it's a one-time thing, or seems to be random when and where it happens, check one of the first few things.
Sometimes, it isn't you.
If an area is loading when it happens, though, there is something else to note. How far along did the "progress bar" get before the game crashed? Seanas wrote this a while ago, and I saved it. I'm posting it here in hopes that it will help someone else.
as to which file is the cause, yuo can tell by how far thru the loading process you get. if immediate black screen of death: corrupted creature listed in the .are file; if it makes it approx 1/3 thru loading screen: corrupted .are file; if almost the whole way: something corrupted aded via the .bcs file; if the whole way, area brielfy shows then CTD: animation conflict.
That's when your weidu.log will help.
Here's hoping that this will make it easier for folks to more accurately report their gameplay problems, and easier for modders to help them solve them.