Volt and I may have located the problem which causes /some/ players to crash inside Deganwy. After many crashes, I decided to fiddle with the graphical settings. And we found that if you click on "Enable Shiny Water" in advanced video options, our GFX cards get overloaded and eventually it'll crash when facing or looking in the direction of the
water basin here.
I will add that I've encountered the same crash in other areas, though without the overload or FPS drop first. But both causing a TDR crash.