Users who have updated to iPhone OS 2.2 are facing some significant issues, including problems with third-party apps, Internet connection issues, problems deleting email and more.
Third-party Applications broken Some third-party applications will no longer function properly under iPhone OS 2.2 due to API changes and other modifications. These include a number of applications that make use of CoreAudio. These applications will generally need to be updated by their developers. However, you can try uninstalling then reinstalling applications for problems that do not involve API or other strict compatibility problems.
"Could not Connect to Internet" Some users are encountering an inability to connect to the Internet over cellular networks after the iPhone OS 2.2 update. In some cases, this issue can be resolved by switching from 3G to EDGE (or, for carriers other than AT&T, the appropriate GPRS network).
"SIM card not inserted" or PIN lock Some users are receiving an error message indicating that the SIM card is not inserted, or that a PIN lock is in place when none should exist.
The SIM recognition issue can sometimes be resolved by removing the iPhone?s SIM card, then connecting it to your computer and restoring. iTunes may then reload the iPhone software successfully, after which you can re-insert the SIM card and attempt synchronization with iTunes.
If you get the PIN lock message, try the suggestions in this tech note.
Kilometers instead of miles in Google Maps It appears that Google Maps for the iPhone now displays kilometers instead of miles for various countries. You can temporarily resolve the issue by selecting 'USA' in International settings, though this obviously introduces other problems for users outside the U.S.
Problems deleting email Some users are unable to delete emails from certain accounts, especially AOL accounts after the 2.2 update. This problem can generally be resolved by navigating Settings > Mail, Contacts, Calendars > (Your account name) > Advanced > Deleted Mailbox, then setting for the "On My iPhone" Trash for a POP account, or "On the Server" for an IMAP account.
App Store extremely slow The App Store is extremely slow after the iPhone OS 2.2 update for some users. This may be a server-side problem that Apple will resolved shortly.