To get everything in one place, please can you post a DXDiag report so we know your hardware, os and drivers. Secondly have you *ever* used mods (even if you disabled them) as sometimes left over mods can cause issues. A quick way to check this is to add the command line option '--nomods' to prevent PA loading any mods from anywhere (this is either in the settings in the Uber launcher, or I think somewhere in the game properties in Steam). Another thing that is worth checking is to verify your game files (in the Uber launcher just click 'Verify', again I think you need to go into properties in steam and verify the game cache although as I don't use steam for PA I'm not 100% on that). It could be that the files related to the lava shader are broken or missing. Final thought is you could try performing a clean boot in case 3rd party software is interfering with PA somehow: https://support.microsoft.com/en-gb/kb/929135 Hope that helps!
I downloaded my first mod for it yesterday, but that isn't the cause because it's been like this ever since I bought the game in January of 2015. I verified the game, still white lava and black terrain. Here is the DxDiag.
Yeah, that's not up-to-date drivers. Try downloading the drivers directly from NVidia: http://www.nvidia.com/download/driverResults.aspx/87783/en-us
Yeah 600 series cards are fully supported on latest nVidia driver which came out a couple of weeks ago for Windows 10. Don't download from Lenovo (manufacturers never keep the drivers page up to date once they ship a machine). Use the link DeathByDenim gave you and you should be fine