Recently, I have been having troubles modifying, adding, and rescheduling events in my Outlook 2007 Calendar. Whenever I try to make a change or addition, the event reverts to it's previous state, or just disappears. When re-open an event that reverted, there is an information bar at the top that says: This item was not completely updated during the last server synchronization. Click here to review other versions. When I click the ribbon bar, I get the option to "View Local Failures." When I do this, it opens up a new window very similar to Outlook except with a series of failed events instead of messages. However, there are no special options, it merely seems like another instance of Outlook renamed "Local Failures." I have tried searching other places, hoping to possibly find a log file of some sort of the activity and the error. I returned to Outlook, and changed my sidebar view ot Folder List. I displayed the folder 'Sync issues,' and there were numerous items with subject "Synchronization Log: " Here is what the logs in this folder look like: 17:24:06 Synchronizer Version 12.0.4518 17:24:06 Synchronizing Mailbox 'Name' 17:24:06 Synchronizing local changes in folder 'Calendar' 17:24:06 Uploading to server 'Exchange server 17:24:06 Error synchronizing message 'Event Name' 17:24:06 [80040900-3EE-80040900-323] 17:24:06 Unknown Error. 17:24:06 Microsoft Exchange Information Store 17:24:06 For more information on this failure, click the URL below: 17:24:06 http://www.microsoft.com/support/prodredirect/outlook2000_us.asp?err=80040900-3ee-80040900-323 17:24:07 Moved a message that failed synchronization to 'Local Failures'. Message subject -> 'Event name'. You can view this message in your offline folder file only. 17:24:07 Synchronizing server changes in folder 'Conflicts' 17:24:07 Downloading from server 'Exchange server' 17:24:07 1 item(s) added to offline folder 17:24:07 Done The link just brings me to the Microsoft support page, which again leads to another dead end. I have Googled numerous different key words relevant to this error, but to no avail. Is anybody else experiencing this? And if so, have you figured out a way around it? The calendar has become pretty useless since it stopped functioning Thanks in advance for any help, Steve