Have you tried turning off and on your pc again?
But now for real: Haven't played minecraft in a while but when I checked last, large issues occured when using custom shader settings/trying to overwrite texture pack settings. Did you check into this? Otherwise try to iterate other texture packs to find out if the problem persists (then it is obviously a shader problem).. If that doesn't help you have to go through all hardware expensive settings in the shader tab as you might be limited by ressources.