Crash in single player at startup after months of no issues

[Hovdavic]

Weird problem here. I think something must have happened to my machine, because I have been playing the game with no issues for months, and even played earlier today with no issues. But just now when I tried to load a world after the game started I got this message at the end of load:

Here is my client-main.txt file

Any ideas?

I tried loading another world and had the same error. I restarted the machine and got the same error. It just seems so random. I know this might be a tough one but I thought I'd give it a try. 

thanks in advance

client-main.txt

[l33tmaan]

I don't speak code, but the file looks like it's crying about an OpenGL shader rendering improperly or something. Did you perhaps update your computer or other software recently? 

[Hovdavic]

I didn't update anything *on purpose* but the only thing I can think of that might have updated is my antivirus definitions, or *possibly* windows, although I have had those updates blocked for a couple of years - something could have snuck in somehow... who knows. After trying to reinstall the game program (no change, it still crashed) I decided to mess with the graphics settings in the game settings before opening a world. I lowered the graphics from "high" to "pathetic" and loaded a simple creative world, and... it worked! So I exited, and upped it one level, reopened the world and it loaded. I did this repeatedly, each time upping the level. I got to medium, the one below High, and it loaded. Then within the world I escaped to the menu and changed the graphics from medium to high, and it didn't crash. I exited the world and tried to open a the world (with the graphics set to high) and... it crashed like before. 

So my "solution" is to run the game on Medium graphics setting instead of the High setting and it seems to work just as well as it did before this weirdness started. I can't imagine what could have shifted in my PC environment to create a conflict where none existed before. But, at least I can play the game again, which is the most important thing. 

Thanks for responding. 

If anyone else has a sense of what it could be I'd be interested to hear from you, but the intensity of this post has gone from "HELP!" to "I'm curious..."