Comment 17 for bug 432176

The original reporter says that Alpha 5 fails to boot for them as well, so it has to be unrelated to any boot migration changes.

Also reading the description, the reporter describes seeing the Ubuntu Logo with moving lines, ie. the xsplash screen as it existed in Alpha 6. He also confirms seeing a spinning pointer. You would only see a mouse pointer if X was running.

The screen goes black, and then the logo sequence starts again.

This description is consistent with a crashing X server.