I have 2 PS3's under my TV.
One died last month wih BR drive failure but has a HUGE HDD in it with tons of my PSN games...so thats what its used for (I really dont feel like formatting it, copying files, re-downloading 100's of games)
My new model, a month old with standard HDD, I use for disc based stuff and will be upgrading the HDD for my further PSN purchases.
My new model has had 4 Starhawk freezes (up till yesterday morning when I sold the game) All of which have been in the hom screen during gameplay. Usually when accessing the skills menu.
So, dont think its the model, HDD, etc...
edit: I did the rebuild thing a million times with my PS3 with the big HDD and tons of games. I guess when the BR drive was failing freezes became a common occurence, maybe 1 or 2 a day. So everytime I rebooted my PS3 afetr a freeze it would ask me to "rebuild the HDD" or whatever. I did that rebuilding shit a ton of times before I just started hitting "cancel" instead of waiting for it to rebuild.