I have an iphone 4 running 4.2.1 I jailbroke the phone using redsnow. I tried installing calendar lock and it totally locked up my phone. The app installed with out an issue, I clicked reboot phone when the app was finished installing, then the phone would just sit on the black screen with the apple icon in the middle of it. I had to restore my phone to get it working again. I tried different calendar apps and they all did the samething. I also had the same issue with the volume boost. Most of the postings I've found state that these apps work in the i4 with the firmware I'm running. Any suggestions would be greatly appreciated. Thanks 