Help Identifying an Anime

[Premsyl]

I saw this ages ago, when Sci-Fi channel was still playing Anime from time to time. Let me see how much I can remember.

Bunch of kids in a high school setting or something. The city around them starts going all wonky and some of them start realizing that they're often repeating the same day over and over again (Groundhog day style). At one point the school becomes half submerged in a lake, at another point they fly a plane out and find out that their little world is sitting on a giant stone turtle floating in space (Yeah, weird). Ultimately I think it's revealed that the entire thing is some matrix-esque computer program conjured up by some little dwarf guy wearing red. Help me out, if you can.

[Closet_Skeleton]

I've seen it bits of it. I can't remember what it's called though, I just remember it being quite old.

Is is a movie or a series? I think it was a movie.

[Premsyl]

Movie. I remember spending like at least an hour watching it.

[Closet_Skeleton]

It isn't this is it? http://www.abcb.com/parents/dreamer.htm

It's a movie based of a Manga where the director did his own thing with the liscense and it doesn't really reflect the source material.

I couldn't find a more detailed synopsis, but I vaguely remember this film being a bit like that.

[Premsyl]

Seems like that's it. The description seems to nail everything I remember about it. I appreciate the help.