Outlook: Problems Syncing Offline Folders
From: MS KB 842284
How to create a new .ost file and synchronize the folders
To create a new .ost file, rename the old .ost file, and then synchronize the new .ost file with the computer that is running Microsoft Exchange Server. When you rename the old .ost file, Outlook creates a new file. To do this, follow these steps:
1. Quit all programs.
2. Click Start, point to Search, and then click For Files or Folders.
3. In the search dialog box, click All files and folders.
4. In the All or part of the file name tab, type *.ost .
5. Do not type anything in the A word or phrase in the file box.
6. Click the hard disk in the Look in list. Then, under the More advanced options option, click to select the Include subfolders check box, and then click Search
In the Name column, you see the .ost file. The default location for the .ost file is as follows.
For Microsoft Windows 95 and Microsoft Windows 98:
C:\Windows\Local Settings\Application Data\Microsoft\Outlook
For Microsoft Windows 2000, Microsoft Windows NT and Microsoft Windows XP:
C:\Documents and Settings\user name\Local Settings\Application Data\Microsoft\Outlook
7. Right-click the .ost file, and then click Rename. Rename the file by using a different file name extension, such as an .old file name extension instead of the .ost file name extension.
8. On the File menu, click Close.
9. Start Outlook, point to Send/receive on the Tools menu, and then click Send/Receive All.
You see the status of the new synchronization in the lower-right part of the screen, and you now have a new .ost file.
Because the .ost file is a replication of the information that is stored in the Exchange Server mailbox, this procedure does not damage any information.