visualization problem

hi,

I think this one goes to David

I stumbled upon this little problem and don´t know what to do. In class at the university some students are working with a file that started to make some visualization problems. I thought it was because their graphics card was not very good, but I´ve tried it in several computers, stronger ones, and the problem is still there.

is a problem with the file itself or it can be solved?

(sorry if the file is rather messed up!)