Mac OSX has been freezing since 2002
Have had my mac pro since 2008 - Snow Leopard since 2009 -- never experienced a freeze until November when I was cleaning up files and also adding text to pictures with Photoshop CS3.
I did al of the things apple and this help said to do with changing clock battery, resetting pram - etc - and still without doing much of anything problems on startup - finally found one poster who pretty much said let that frozen startup run.
I have an OSX book written by Bob LeVitus in 2002 -- with OSX freezing -- reset pram etc - but it did mention a Finder freeze (and after searching logs finder indexing did cause a memory leak)
In the End - let the slow powerups run - then restart I pretty much shutdown Spotlight/indexing by moving my time machine drive into private along with my folders and my Cache in my Library -- and also deleting what turned out to be 1 corrupt Iphoto library from both the desktop and my time machine -- reselected the time machine drive.
In letting the long startups run and removing the iphoto libraries both my Time Machine and Hard drive are now less than 50% filled. - and only letting spotlight look at folders - nothing else -- my Mac is now totally back to a quick startup.
The problem as I see it with the freezes is somewhere in the base Unix and OSX handling of the disk drives and memory -- Finder/Spotlight if indexing everything can cause major freezing when you drive is getting filled (or possibly fragmented). The more stuff you are running at the same time - the more likely you are to get a freeze and as you cannot see what is going on not much you can do about it -- so its up to those of you with the latest versions to start shouting at apple to start fixing the underpinnings.