Apple’s patches have generally worked well for me. The latest 10.4.11 patch for Mac OS X 10.4 (Tiger) also brings Safari 3 for Tiger users alongside fixes. I usually apply the software updates pretty fast, usually a couple of days since the release, at most. I’ve probably been in luck, since this is the first update I’ve had problems with.
I’m not alone with my problems, apparently, as there have been reports of the update breaking the system to a point where it doesn’t even get past startup.
I chose to install the update for my Mac Mini through the software update a bit after it became available. Download went fine, but the installer decided I wasn’t ready for the future and quit installing less than halfway through. After that it threw the install package to trash. Ok, I thought, decided to reboot and try again - just in case anything funky was going on.
This proved to be a mistake. Mac Mini didn’t seem to be able to locate the startup disk anymore, getting stuck on grey loading screen flashing with folder icon and question mark. First thoughts were hardware failure, and - sure enough - Apple Hardware Test indicated a memory error.

I replaced the faulty memory, tested again and it came out ok. Yet OS X refused to start. Checked the disk with my laptop only to find out it was fine, and finally chose to do a repair install on OSX. After that everything was back to normal, except Safari kept crashing constantly and identified itself as version 3 while rest of the system was still version 10.4.10. Because of the unsuccessful update? Let’s try it again. No dice. Again a failed install and a system unable to boot…
Reinstall #2 returned things to normal (aside from a still broken Safari). This time I decided to download the combo update and guess what, it installed with no problems whatsoever. Everything still worked after reboot and even Safari was back to normal.
Now, had I downloaded the 350 megabyte combo in the first place, none of this would’ve happened. Except the faulty RAM, of course. That sucked. Unfortunately, I installed the 110 MB package that came through software update and so did many others. Makes me think that either someone at Apple slept through the testing phase or none of their systems suffered from this. Or they tested with the combo update…
Amusingly the PowerPC-version of the same update that botched up an Intel Mac Mini did not have any issues with my iBook G4. Magic of working RAM I guess. Wonder what are the odds of memory going bad just as you install a system update?