Skin glitch in multiplayer and singleplayer

I've been having a problem where I would hop onto a singleplayer or multiplayer server and my skin, nor anybody else's skins would show. If the server had custom heads, they would not show either, and after a week or so, it has become sort of boring seeing the same things over and over again. I have attached a Trend Micro Hijackthis log from my computer onto this. Can I please get help with this problem ASAP?