Randomly, Gothic 2 (with Night of the Raven installed) crashes. The first time I encountered it was in the tower with Xardas, asking a specific question regarding the tower (he mentions people building it, I reply, and it locks - forcing me to reboot). And just now, I was walking in the city... and it locked up again, forcing me to reboot. (I am forced to reboot due to it not letting me close it with CTRL-ALT-DEL)
Does anyone have these problems, and if so, is there a way to go about fixing them?

Find me a game that doesn't crash from time to time. Gothic games are unstable, all of them. Random crashes happen quite often. Nothing to worry about,

Try the community patches on World of Gothic....

The only community patch for Gothic II was the Ironkeep patch, no? And it really didn't fix any of the crashing bugs, apparently. Anyways - the problem has escalated to the point where I start the game, Xardas talks - and then it gives the visual for him to talk again - but never does. I can open inventory, and all that... but he never gives his dialogue and, for whatever reason, I can't escape the dialogue.

This problem sounds like something more significant than just a random bug.
Have you tried reinstalling? Also, when you installed it, did you skip the integrity verification step? Also, have you updated DirectX lately?

I have the most recent version of DirectX (according to http://filehippo.com/download_directx/). This started happening on the reinstall. Prior to it, I was able to make it into the city. Now I can't even get passed Xard's initial conversation after the video.
Is there some sort of bug when you skip dialog with ESC? I've found some info on it dialogue never coming due to a memory leak that wasn't fixed, but not how to fix it.

Didn't see your OS so . . .
If using Vista/Windows 7 . . .
Make sure, when installing the game, that you right click the setup exe and click "Run as administrator" from the dialog. If you only double click the exe, without doing the above, Vista/Win 7 may block some disk writes the game tries to do.
After Installing, right click the game icon, click Properties, click Compatibility and check mark the "Run this program as an administrator" option.
If using Vista/Win 7/ XP . . .
Make sure you have the latest video drivers . . .
Click here for ATI
Click here for Nvidia
any other video card you will have to find.
One last thing to try is disable anisotropical filtering and anti-aliasing in your video card settings. XP right click the desktop, click properties, Settings, Advanced, your card tab. Vista right click desktop, click Personalize, Display Settings, Advanced Setting, your card tab. Can't tell you where, you may not even be able to disable these setting depending on the card. If this makes no difference . . . enable them again.
Gothic 2 is notorious for crashing, good luck.
Edit: when the game is up and running, Alt-Tab to the desktop and see if your firewall has raised any dialogs that need to be accepted, some firewalls, mine is Comodo, need confirmation to allow an exe to do certain things the first time, once accepted, it will not ask you again and will allow the operation from then on. If you don't confirm, it will block the disk write or whatever. Games are known to ignore the dialogs so you might need to "go look" for yourself. Setting the game exe as a trusted program can eliminate this problem but could be dangerous if the exe is on-line capable.
Edit 2: If you have a dual core AMD processor, you might consider giving the AMD Dual Core Optimizer a try. It helped Painkiller to run smoothly on my laptop. It doesn't have a GUI but installs and runs in the background. Can't see that it has affected anything other than PK runs better. It can be uninstalled using control panel. IT IS NOT FOR INTEL CPU's

It happens to me too, exactly the same. I have aspire 5739g, nvidia geforce gt130m with vista 32, i have tried updating the drivers, and direct x to no avail