When loading up Minecraft with the game's "texture pack" (resource pack now?) set to a texture pack with 32x32 resolution text, the text of the game becomes glitched, even when you switch back to the default texture pack without closing. However, if the game starts up with the default texture pack selected, switching to the texture pack with the higher resolution text has no issues.

This occurs in every Minecraft Snapshot since the inclusion of resource packs, up to the most recent 13w25c snapshot.