Random_Coffee: A friend had a similar problem after upgrading to Windows 10. One of the drivers did not work properly after the upgrade, resulting in a memory leak. His RAM-usage would keep going until there was no more available RAM, and the PC bluescreened. Reinstalling the driver solved it. Have you upgraded your operating system recently?
Smeggins: dont have windows 10. Still use 7 ultimate 64
Windows 10 is free for you, you know. On balance I've found it a good deal more backwards compatible with games than Win7. I also went from Win7 to Win8.1 before I went to 10, and I found that even 8/.1 was better than Win7 in terms of game support. From now on Microsoft will be putting 100% of its R&D into Win10. No R&D will go into Win7/8--Win7 will get security patching until early 2020--Windows 8 for longer. But all of the new (and hopefully better stuff) is all going into Win10 from now on. Hopefully you are planning to take advantage of the free upgrade before July/29/2016--because after that the freebie upgrade drops off.
You should be aware that AMD is moving to WDDM 2.0 support for its GPUs--including the 7970 (the entire 7000 series & up, in fact.) Don't know if that's your problem, but WDDM 2.0 is not supported by Windows 7. Neither is d3d12, which is also being developed for.
I don't have the symptoms you describe with w3--game shuts down instantly. But I'm using the Crimson drivers inside the Catalyst CC shell (works great), Win10x64 v1511, AMD FX-8320e, AMD R9 380 4GB. I can't recall ever even having a CTD--game has been rock-solid. running patch 1.11 with the first expansion for the game installed.
I'd suggest reinstalling the game from scratch, and then reinstalling your gpu drivers. You've still got time to go to Win10 but as stable as it is I wouldn't waste time clinging to yesterday...;) Hope you can get it sorted...!