describe "froze". Did the screen become unresponsive but display something? Did it go black? Did the soft buttons remain lit? What were you doing when it froze? How did you unfreeze it? How long was it frozen for?
I had a horrible freeze/lockup problem that could only be remedied by removing the battery. When I sent it in to have the screen replaced after dropping it, i also had them flash the rom. I assume they did this. I have no way of knowing whether they did because all they cared about was the broken screen even though the main reason I sent it in was to fix the freezing problem.
Since getting it back it's only locked up on me twice, and both times I was turning the gps on or off. It was more of a reboot than a freeze. The soft buttons stayed lit, the screen stayed black and unresponsive, and it recovered on its own within about one minute. I can't repeat this. I just now tested and turned gps on and off without a problem (though I did not give it a chance to lock onto any sattelites).
but beyond that the phone is perfect now. I literally have no problems with it. It's perfectly responsive and not sluggish or quirky. I've got my fingers crossed.
So if you are having the problem I had, you need to have your rom reflashed. To avoid voiding your warranty you'll have to send it to Samsung which takes about a week and a half including shipping time. They pay for 2nd day shipping from and to you.