Nobody in Particular Code Lyoko : Season 3 Episode 10

During a test to materialize Ulrich directly into Sector 5, his mind and body become separated, leaving Ulrich's body trapped on Lyoko and his spirit stuck on Earth. What's worse, Xana possesses Ulrich's body and uses it to attack the core. Meanwhile, Susan, disappointed with Ulrich's bad grades, tries to place him in remedial classes.