Do I have to plug my Apple TV in to a computer

With a USB cable.

No, you plug it into the wall outlet. You only need your computer if you want to acess your iTunes over your Apple TV for music, still you dont need to plug into your computer

Ignore this post. It was ment for another thread and it will not let me delete it now.

You don't plug it in to a computer at all. You can connect it to a computer over your home network if you it to play content from that computer but you do not have to.

Do you know if there's any reason the Apple TV would make me connect to iTunes on a computer via usb?

I just bouth an Apple TV and it was working fine until I updated the software and now it's stuck on a screen that tells me to connect to iTunes via usb. I've tried to unplug the power chord and plug it back in, but I still get the same screen.