The image from Jeangunner's post:
(btw, you cant use the imgur url as the image url, you need the actual image url)
Ive noticed it will sometimes load like that and sometimes it will load normal. Same thing with lava. The only thing i can think of is try turning off No Slide. The code that prevents you from moving on the slides might be preventing them from animating correctly. If that doesnt fix it then i have no idea.
Edit: i just checked out some videos on youtube that are all posted pretty recently and there are a bunch that have the small squares look but still cause the person to slide. Im really not sure if this is something caused by a hacked client or if regular clients can experiences the problem too. If it is only an issue on hacked clients, then people really need to stop posting videos while using hacked clients lol