I'm not sure if this is related or not, but I thought I'd throw it out there just in case it helps. I'm a freak when it comes to knowing why certain things are on my computer, so I've constantly going through files on my linux system trying to figure out what exactly they do. Well, beginning with 7.2, RedHat began to create a /initrd directory. Since I'd never seen it before, I took a look at it and it was empty. Hmm.. that's weird, well, if there's nothing in it, then I'll just delete it... Bad idea. The system never would come back up until I booted into rescue mode and recreated that directory manually. Apparenty the system copies temporary files into that directory during bootup or something, because it definitely needs that empty directory.

Also , have you gone through the mkinitrd process? I don't remember the exact process, but I'm sure you can google it. It's also an integral part of installing a new kernel, but it's a little less obvious.