When using iDisk Sync, the copy of your iDisk on your desktop may not successfully sync with MobileMe after you copy files to it.
Click the Sync icon to the right of your iDisk icon in the Finder sidebar to initiate a manual sync.
If that does not resolve the issue, you should troubleshoot iDisk syncing. Make sure you back up any files that only exist on your iDisk. If a file only exists on your local iDisk copy, be sure to drag a copy of it to your desktop or another location off iDisk prior to any troubleshooting. If a file you are expecting to see no longer appears on your iDisk, see iDisk Sync: Data unexpectedly appears to be missing from your iDisk.
Follow these steps to troubleshoot your iDisk, verifying each one and stopping if you resolve the issue:
Make sure your Internet connection is working as expected.
Make sure you can connect to MobileMe and view your iDisk via your Web Browser at
http://www.me.com/idisk.
Download and install the latest available version of Mac OS X.
Note: If you are already using the latest version of Mac OS X (nothing appears in Software Update), restart your computer, then go to step 4. Apple recommends using Mac OS X v10.5.8 or Mac OS X v10.6.2 or later if you are syncing your iDisk.
Try syncing your iDisk again.
Make sure you have enough free space available on your Mac OS X volume for iDisk Sync, as it requires space on your hard drive in order to work. The amount of space necessary varies with different versions of Mac OS X. Click here for more details on the how much space iDisk Syncing requires. If you do not have enough free space, disable iDisk Sync (click the Stop button in the iDisk pane of the MobileMe System Preferences), or reduce the size of your iDisk before enabling iDisk Sync.
Make sure you can connect to iDisk in the Finder. You can test basic iDisk functionality by connecting to another user's iDisk Public folder via the Finder Go menu. Select Go > iDisk > Other User's Public folder and then enter another user's valid MobileMe Member Name, such as emily_parker. If you're unable to connect to a valid Public folder in the Finder, you should troubleshoot your connectivity to iDisk, as you must be able to first connect to iDisk reliably in order for iDisk syncing to work.
Set your iDisk to Manual Sync on any computers that are using iDisk Synchronization with your MobileMe account.
Open System Preferences by choosing System Preferences from the Apple () menu.
Click the MobileMe System Preference.
Click the iDisk tab.
In the iDisk Sync section, set the Update selection to Manually.
Close the MobileMe System Preference.
Note: When you use manual syncing, you will need to manually trigger iDisk Sync activity by clicking the Sync icon to the right of your iDisk in the Finder sidebar. Manually syncing is especially important if you sync multiple computers and you are using a moderate to large amount of data stored on your iDisk. iDisk Sync can only occur with one computer at a time, so you will want to optimize your experience from each computer you use, so as not to possibly generate schedule conflicts or prevent the computer you are currently using from syncing. If you use multiple computers but use one of them more than the others, you may wish to configure your most used computer for Automatic syncing and set the others up for manual syncing. Doing this would help you avoid having unused computers block syncing of your actively used computer.
Restart your computer, especially after making any major changes to your Sync settings or if you are having trouble connecting to iDisk. Restarting your computer is a great way to completely relaunch all of the networking frameworks and services on Mac OS X.
Confirm your keychain is working as expected.
If you are still unable to sync your iDisk, contact MobileMe support.
Additional Information
You can sometimes find more information about iDisk activity by viewing the log files associated with iDisk and iDisk syncing. Log files sometimes display an overwhelming amount of technical information, but they can be useful for Developers and other highly technical users. iDisk writes alert, warning, and other log entries to the All Messages and Console Logs, so you can use the Console utility to review your log files if you so wish. iDisk syncing writes these entries to the FileSyncAgent.log and the FileSyncAgent-verbose.log, both of which are also viewable via the Console.