I bet you're using Nvidia graphic card, and if you do, go to Nvidia Control Panel -> Manage 3D settings and turn off "Threaded optimisation" setting and it should be solved. I had the exact same issue when this option was enabled and it wasn't just in Minecraft.
If you're using an ATI/AMD Graphic card, go to Catalyst Control Center, select advanced settings, select graphics and then 3D and "Use Application Settings" for Anti-Aliasing and Anisotropic Filtering.
Christoffer
I bet you're using Nvidia graphic card, and if you do, go to Nvidia Control Panel -> Manage 3D settings and turn off "Threaded optimisation" setting and it should be solved. I had the exact same issue when this option was enabled and it wasn't just in Minecraft.
If you're using an ATI/AMD Graphic card, go to Catalyst Control Center, select advanced settings, select graphics and then 3D and "Use Application Settings" for Anti-Aliasing and Anisotropic Filtering.
I hope this helps you!