iOS 4 on iPhone and iPad and Exchange 2003 just don't seem to be playing nicely together, especially when it comes to Calendar events -- they mysteriously disappear from ActiveSync, invitation replies refuse to send, and, well, don't get me started.
Both problems are serious for enterprise users. In the first you create or accept and Exchange event invitation, it gets added to your Calendar, and then -- poof! -- it's gone. But only from ActiveSync. If you look in Outlook or OWA (web interface) it's still there. If you're relying on ActiveSync on your iPhone or iPad, you could miss your meeting, call, conference sessions, etc.
The second involves receiving an Exchange invitation and trying to accept or decline it and being told your message can't be sent:
Your response to the invitation cannot be sent.
It may not cause you to miss events but it can cause problems for teams trying to keep track of who is attending which event.
For Mac users these problems are exacerbated by both Apple's OS X and Microsoft's Office not supporting Office 2003 over ActiveSync, only Exchange 2007 and later. That leaves OWA (the limited version supported outside Internet Explorer) as the sole way to look at a true representation of your Exchange system.
Since corporate users can seldom if ever force their IT departments to upgrade to Exchange 2007 or 2010, and support for 2003 is already being discontinued and likely won't get a lot of support attention, fixes may be few and far between.
Anyone else experiencing these or other problems with iOS 4 (iOS 4.0, iOS 4.1, or iOS 4.2) and Exchange 2003? Any workaround you've figured out -- other than copying events to Google Calendar for safe keeping?
Let me know in the comments and help us trouble shoot in the iPhone Forum.