Fedora :: Boot Randomly Hangs And Waits For Keyboard Input

I have a very strange problem with Fedora 13 on my home PC. When booting it just hangs at random points in the boot process. When it happend the first time, I thought the PC probably is completed frozen, but then I discovered that hitting the return button got the boot process going on again, but just step by step. That means on every boot I have to keep hitting the return button until gnome starts up, that's very annoying. So for any reason the boot process seems to switch to interactive mode somehow...

I already removed the kernel boot options rhgb and quiet to see, where exactly this happens in the boot process. But as I said, it seems to be completely random. Sometimes it's when "Starting udev", sometimes, when setting up eth card, when starting atd, and so on. It's different every time.

By the way, a similar thing happens when shutting down. It can take up to half an hour until the PC really shuts down. But it's usually going faster if I just keep hitting return after issueing the shutdown command (which actually looks a bit dull). But the PC finally shuts down at some point. That's not the case when booting up. I thought, maybe there's some kind of timeout problem. But even waiting for two hours, the PC does not startup without keeping hammering the return button