I purchased the game today, and am experiencing this problem.
I'm running on Windows 7 64-bit.
No other games have given me this issue.

Steps I have taken to fix it:
*Restarting Steam
*Running directly from .exe
*Rebooting computer
*Verifying integrity of game cache
*Reinstalling the game
*Disabling in-game Steam Community

Nothing has seemed to help so far.

Ran Steam as Admin. Didn't fix the problem.

I have uploaded and attached the dxdiag and DayZ files here as "DayZ Troubleshoot.rar".

I was able to work around this problem by uninstalling and reinstalling Steam.
Anyone else having this problem please note that, if you choose to reinstall Steam, you will also have to reinstall all of your games. But, if I am correct, any achievements and save data should remain intact (please correct me if I'm wrong).

I will upload the files from C:\Users\<Name>\AppData\Local\DayZ\ for you again, in case anything has changed, as "Working DayZ Troubleshoot.rar"

Thanks for the support, komin. Please let me know if I can continue to provide any further information.

1. I will disable all other programs/utilities that I can and try again.

2. Nothing is overclocked.

3. I will disable all other programs/utilities that I can and try again.

4. That is correct. Here's more information on my graphics card. http://www.game-debate.com/hardware/?gid=490&graphics=Radeon%20HD%206550D

5. Correct. 3x2GB

Edit: I followed the steps above. Still experiencing the problem.