Oddly enough, when I was fiddling with my new graphics card and swapping cable modules around, I ended up plugging both PCI-E power adapters for my 580 Ti into the same bank on my PSU. The result of this was an immediate crash when logging into the game; launch didn't crash but as soon as I typed in the passwords and pressed enter, hard-core vegas lockup. I moved the 6-pin adapter to the other PCI-E bank and it's been stable since. Just one of those things where if you're hitting the power limits on your PSU, it can cause bat-shit crazy effects that make NO sense from a software/config/etc. perspective.