I guess DD was good while it lasted because I cannot get past the crash that occurs when I'm facing the boss in the dungeon beneath the rogue dwarf camp. I click on the floor tile which sends me down into the level below. The sorceress (or whatever she is) says something, I reply, "x" out of the dialog box and it goes black -- every time. I've tried different resolutions, setting, etcetera, and it still goes black at that point -- every time.
Oh, well. I enjoyed the game to this point and am disappointed that I can't complete it. By the way, how much more did I have to do once I completed the Council quest? Was I close to the end or was there a significant ways yet to go?

There is a lot more to do. You are describing a bug in the unpatched version. On the start up screen, what version does it say in the bottom right corner. Should be V1.005A if you are running the patched version. Also will tell you the version number on the save screen after selecting a save. If you are not running V1.005A than you need to backup your saves and redownload the setup.exe. Uninstall the game, delete any directories under the GOG\Divine Divinity location or in the location you installed it. After reinstalling, move your saves back into the new install. It should open them and the problem will be gone with the last patched version.
Right-click the new setup.exe, click "Run as an administrator" and reinstall. After installing, right click the game short cut, click Properties, click the Compatibility tab and check "Run this program as an administrator". I uncheck "Run this program in compatibility mode for" to begin with, especially for Win 7.
If none of the above applies to you (you ARE running the newest version) make sure you have the short cut checked as described above.
You may also want to use RunFirst if you have a dual CPU to set the affinity to one core while playing as some system have trouble running DD on multiple cores, a sound problem is a good indication you need RunFirst. Look at this thread for a link to download the program (it's free and small) and for an example of how you should enter the path to RunFirst in the target path on the shortcut tab of your game. You must have a dual core to use this program.
Hope this helps . . .=)

You were absolutely correct. I was running ver 1.00.4a and not the patched version. I did everything you said to do and it worked out (so far). Now it's just a matter of figuring out how to defeat the boss. Damned spiky things coming out of the ground.

That's great, you will REALLY like playing it now, not many of us were able to play that far into the game without complaining loudly . . =)
Should be MUCH better for you now . .
Edit: BTW, there were several quest that couldn't be completed so you might want to go back and retry them, the church north of the cursed Abby and a few more. Anything you couldn't do before . . . you should retry . . . the patch fixed lots of bugs . . . =)
**spoiler**
If you are a warrior, get lots of shadow potion and use your special move. Using the special move does not make you visible and she can't spike what she can't see. You can right click away and wear her down. If you left click even once, you will become visible and need to take more shadow or suffer the spikes. The dwarfs are really Orcs so lightning will do a number on them but I just used the special move on them as well. Also, try freezing her . . .=)