Yesterday I started downloading Xcode 4 to my iMac. It's a very large file, around 4 GB. The next day I found that only 2 GB of it is downloaded and the download had stopped. Before leaving my computer to download, I disabled the automatic sleep setting. Why did it stop? The computer was still on in the morning, and there was no power failure. Is there any way to find what happened?
It sounds like the server timed out. Just try downloading it again. If you got it through the Mac App Store you can see it and all your purchases under the Purchases tab at the top next to Updates.