Someone help an aspiring Shogun?

[CountMRVHS]

Thanks again, Gregoshi. :)

My computer is a desktop, with Win7.
It's set up a little weird, from what I understand. So it's a 32-bit machine, but with 12 GB of RAM - except that only ~3 GB of RAM are available. One thing I've done is to change the amount of virtual memory to 8GB, but I'm still getting crashes.
Graphics card is an NVidia Geforce GTX 560 Ti. Recently upgraded the driver.
Hard drive (no SSD) - are you looking for the amount of memory available here?
No mods installed.
Graphics setting were originally on the highest setting possible, but I just tried dropping everything down to 'high'; no change in crash behavior. Unit sizes are probably on the highest setting too (120 Yari Ashigaru per unit), and I haven't changed those.

[Red Spot]

deleted 'tl-dr'-post ...

Couple of suggestions. Check you have the minimum specs the game requires, including processor which so far hasnt been named.
32bit only supports 3G of memory. Sell the rest or get a 64bit OS. Now you're 'aging' ~9G out of 12G just for the heck of it ... and yes it does age eventhough your OS does not use it (read up on 'dual channel mode' before you do sell anything though).
8G of pagefile seems extremelly heavy and might just cause more problems than it will ever do good. Specially since you cant just move the pagefile to the physical memory, if needed, since the pagefile is over twice the size of the actually used physical memory. (I honostly cant say much about pagefiles beyond that they are your second choice of memory. As such I have ample memory in my system and have turned off and removed the pagefile completelly.)

Seeing my 'high end' system, specially compared to your specs, has quite some difficulty with (some) ultra settings I'd be amazed when your system would properly run the 'battle game' on anything above normal, possibly low settings. The 32bit thing is killing you here.