Black shadows with blue edges where there should be light

About a week ago, I noticed that areas where there should be light, such as torches, glowstone, lava, etc., is showing up as a black shadow with thin blue edges. Seems to be happening on all servers I use. I have not messed with the settings. I have a GTX 570, 8GB RAM, Intel i7, and 1 TB hard drive. I searched the Forum and Google, but found no problems like this. Please let me know why this is happening and what I can do to fix it.

pics below