User blog comment:Alakar Voidus/Water glitch?/@comment-1840954-20111209111125/@comment-4061970-20111219164932

Because, if your files are corrupted, you are playing your own Terraria, just on an online server. Your files have to be just fine, or else they can cause some nasty glitches. Heck, this water/lava glitch is probably just a client-side thing, which would explain perfectly why.