Same problem here...
Validated the files: everything is fine
Running Windows 8 RP 64bit on an AMD Phenom II X4 955 with a ATI Radeon HD 5770 1GB
Edit:
Am uninstalling and downloading again, to see if something went wrong with the update process
Nope, even after completely installing it again: CTD on initiating ground combat.
I do get to see the loading screen for 1 or 2 seconds then CTD