I finally installed shaders today, after 2+ hours... D: I tried using them in single player and everything was normal. However, I wanted to test them out on emc, but this happened... As you can see, everything in text was covered by these annoying boxes. Even the options screen and home screen were blocked with these evil squares. ;-; Any help please? I can give more info if you need it.
<insert 30 sec. of laughter> (sorry!!) I think I even recognize a few, uhm, faces in there Ok, sorry, I'm in a very funny mood right now: are you sure the texture pack meets the right Minecraft version? Do those match? It seems like a possible classic version mismatch to me (not sure!).
Dig through the options menus to see if there is a custom fonts option. Seems like it's trying to use a font that doesn't exist.
