I've been holding off on 10.5.3 because it seemed to be giving people some real troubles and I've had some issues with 10.5 in general and I'm hesitant because of that. The Spore Creature Creator demo came out today and wouldn't you know, it requires 10.5.3 for some unexplained reason. So I decided to bite the bullet and take the plunge and all of those wonderful metaphors, because I figure what's the worst that could happen. Short answer: complete system meltdown. I did the software update install, and when it told me i would have to restart and then logged me out of all apps, it tried to do the update but said that the package checksum was invalid or something like that. it then proceeded to exit the updater and dump me back out to the desktop. I read on here about some issues with 10.5.3's package being corrupt on some of Apple's mirror sites. So I downloaded the combo package from apple.com and ran that. It seemed to work, and then it asked to restart. I said OK and it rebooted...only I never got past a solid blue screen with the spinning black pinwheel in the center of the screen. It sat there for 45 minutes. I went and had dinner and came back and no change. So I turned it off and back on again. Immediate Kernel Panic! Awful. Single user mode doesn't work, either. Same error. Something about the extension archive having a bad checksum. Open up the system DVD and reboot from there. I look at my TM restore points and it shows 1 restore point (the most recent) as being OS 10.5.3 and the rest being from 10.5.2. OK, so it thinks it successfully installed .3 Great. So I ran disk utility, which by the way showed no errors on the boot drive less than a week ago when i last ran it to repair permissions. It immediately gets my attention because the boot drive is unmounted, which is weird. My other internal drives are mounted and fine, but the boot drive won't mount. I do a verify/repair on it and it fails after saying that the "keys are out of order" Funny thing is my work Mac Pro took the 10.5.3 update and rebooted and never looked back. It was like nothing happened except my uptime reset. Now Time Machine is recovering from one of my earlier backups from today. Only 2.5 hours left on that one. If I get up in the morning and I'm still getting kernel panics, I might just have to boot up in XP to get some work done... I'm typing this on my trusty 10.4 macbook. Sad that I've resorted to calling this thing "trusty." That's a completely relative term, believe me.