My iPhone no longer transfers my appointments to Outlook 2010 when it syncs

Did this begin after entering a specific appointment? Many times, the entry of a specific appointment, or editing one with a recurrance will trigger this type of problem. Have you tested entering an appointment on the computer and seeing if it will sync? Try entering one on the phone and see if it will sync. Many times it will go one way and not the other, and that helps to diagnose the problem. You can also take the time to run scanpst.exe on your outlook.pst file. That can help to find problems. Did you create an appointment with a reminder that is to go off when the appointment is due, rather than a period of time before hand? Sometimes the iPhone has a problem handling the reminder of zero (0) minutes, which means when the appointment is due. One last thing to do is to open iTunes, go to edit, preferences and then reset the sync history.

Okay, to answer some of my other questions. You know about when it started, if you could go back to around that time for appointment entering? You can change your view of appointments to a list view to check for date entry. Do you set reminders, or do you have a default to set reminders on the phone? Have you scanned the pst file, or have you reset the sync history. For resetting the sync history I said edit, preferences. You have to go one further, and that is to the device tab, then you can reset the sync history. See if any of that helps.