@Elzebub: Thank you for your tip, but it didn't work with me
Some news about my problem ("Mine is a Nexus One v.3.4 GRJ22. I´m not having freezing problems, but after the last update, some times my phone restarts by itself while I'm navigating in the browser. I was using the Miren, and uninstaled it to figure it out if the problem was with it, but it keeping restarting")
Two things that I noted:
1. The problem only occurs when I'm using the 3G. Using Wi-fi there's no problem
2. The problem doesn't occurs only while browsing. With another uses too, like the Market.