Apple recently released the iPhone Firmware version 2.0.2. Which is supposed to fix several bugs but ends up with malfunctioning applications. Incase you are having problems using your official Appstore apps on the iPhone 3G V2.0.2 here are a few tricks to help you:
- > Delete all unwanted applications. Reducing the load of applications on the iPhone can ease our the issue and resolve the error.
- > Delete and reinstall all applications: Backup your iPhone data (via iTunes) and use the ‘Erase All Content and Settings’ tab to clear out data.
- > If that doesn’t work then do a RESTORE and setup your iPhone all over again. you will loose all messages and some more data.
- > And lastly you can try downgrading your Apple iTunes on your Mac or Windows.
Complete steps and article here