My international Galaxy S3 started to constantly freeze, lock up and hang. So I decided to factory reset it. Then I figured why wouldn't I also switch to a custom ROM in the process. So I read the tutorials and installed Android Revolution ROM. The freezing problems have become very rare (they didn't completely go away) but this time I got an even worse problem. My phone won't wake up sometimes. It happened again a few minutes ago: The phone would ring (albeit the ringing tone came out laggy), nothing on the screen, I press power button no response, then I take the back cover off and reinsert the battery, boot the phone and look at the call logs but of course it doesn't show who called me. This is getting very frustrating. What seems to be problem?