Happened to me too after a lot of turns. Igot the window "Out of memory" and a window "C++" which stayed empty...until everything CTD. (See image)

A few turns before it happened, images of Black Widows and Trolls were no longer visible in their medaillon when I got the battle window (spiders attacked my caravans almost every turn).

And so the end of the debug file is thousands of the same line telling me:

Debug Message:  WARNING: (CD3D9Renderer) ::CreateTextureFromFile failed to auto generate mip levels for texture: C:\Program Files (x86)\Stardock Games\Elemental\Gfx\Medallions\BlackWidow_Medallion.png.  Attempting to use 1 mip level.
Debug Message:  ERROR: (CD3D9Renderer) ::CreateTextureFromFile failed to create a texture.
Debug Message:  Texture file name: C:\Program Files (x86)\Stardock Games\Elemental\Gfx\Medallions\BlackWidow_Medallion.png  Mip levels: -1  Usage:0

With Black Widow sometimes replaced by "GiantClothed" or "Fertile_Plains"

The debug file seems to big to be sent to pastebin.com...so I had to cut it. But the end was just thousands of lines of the 3 variations of the 3 lines above.

Debug file:

http://pastebin.com/m3914d211

I had a CTD as well that looks like its memory related:

Debug.err http://pastebin.com/f1ecb3abc

few thousand lines of memory errors and then CTD

Had the same after 200+ turns:

Debug.err http://www.binpaste.com/v.php?id=hwumf

dxdiag http://www.binpaste.com/v.php?id=07edq

I used to have the same problem, not being able to get in more than 100 turns before I got an "out of memory" error.  After uninstalling and reinstalling the game, I was able to push a game to 500+ turns before I got bored.  It was the first time I chose to exit the game, rather than the game choosing to exit me. Might be a fluke but give it a try.

At Beta .24 I was getting 30 minutes of game time = CTD (Out of Memory)

At Beta .25  I was getting 15 minutes of game time = CTD (Out of Memory)

As of Beta .255  I am getting ???? = testing ongoing.