UPDATE: These issues have been resolved in iOS 4.0.1. Please update your iOS 4.0 iPhone or iPhone 4 device to the latest version of iOS using the iTunes software. For more information about this particular iOS update, please visit: http://support.apple.com/kb/DL1061

For more details and to find out how to update your iPhone 4 or iPhone iOS 4 device (iPod touch, iPhone 3G, iPhone 3GS), please access the web address below:

http://support.apple.com/kb/TS3398