The crashes... oh, the crashes!

I bought the Shogun 2 collection from Steam last week (it's the one that includes Rise of the Samurai as well as the main campaign and a bunch of clan DLC).

Started up the tutorial straight away, and experienced a freeze during the first battle. After updating my graphics drivers I was able to continue a bit further, but it was still touch-and-go. I got to the siege tutorial battle and had a freeze/crash, at which point I decided I'd just go ahead and see if the actual campaign worked better than the tutorial.

Started up a game as the Otomo and have continued to get crashes. I took the following steps so far:

-scanned for malware (none found)
-verifed integrity of game cache (looked good)
-altered the preferences_scripts.ini to prompt me to choose between dx9 and dx11 on start-up (I choose dx9, since that's supposed to be more stable)
-set my virtual memory in the Performance Options section of my control panel to 8 gig.

The crashes seem to occur most often when I am loading up a battle; the progress bar will be almost finished, then the music will pause for a sec, resume, and then I get a CTD with a generic 'Shogun 2 has stopped working' message. I don't even get to the battlemap. Restarting the game will usually work.

I also get crashes on the battlemap itself. A particularly annoying example last night: I was besieging another clan's capital with a full stack, and they had a full stack as well. They sallied out; the battlemap loaded up; I used Esc to skip the general's speech, and within about 3 seconds of having camera control the game froze and crashed. Tried again and this time I was able to be on the battlemap for a few minutes - long enough to fight with the enemy - before it CTD'd. Eventually I completed the battle, after around 3 CTDs.

The campaign map doesn't give me much trouble, although one time I noticed some visual glitches during a naval battle (the distant landscape looked completely black and 'spiky'), and when I returned to the campaign map things seemed really... strange. Land and water in the wrong place; that sort of thing. I tried to return to the main menu, CTD'd, restarted and reloaded and things were back to normal.

So, some things I haven't done yet:

-Updating sound drivers. This seems more complicated than updating graphics drivers. For one thing, NVidia has a fairly easy automated process I could follow. But my sound drivers... I'm honestly not even sure which ones I have. I looked through my control panel and had the computer search for new drivers, but it claimed everything was up to date - I find that hard to believe, since the most recent date on those drivers is 2011.
-Running Steam as an administrator. Not sure if this would help, but I've read some people have luck with this.
-Ditching Google Chrome. Again, I don't know how this would help anything, but it seems to be a problem for some.

Does anyone have any ideas as to what might be causing these crashes, and how to prevent them? I've never had such trouble with a game before, and it's beyond frustrating that I can play the thing just fine sometimes but around 2/3 of the time I get these inexplicable crashes.