Repairing an Offline Folder file (.ost)

You may want to scan and repair your .ost if you:
• Encounter a large numbers of conflict items.
• Cannot open particular Outlook items when offline.
• Receive unexpected synchronization error messages (as shown in the synchronization log in the Deleted Items folder).
• Receive the message:
Unable to expand the folder. The set of folders could not be opened. Errors could have been detected in the file drive:\Documents and Settings\user\Local Settings\Application Data\Microsoft\Outlook\Outlook.ost. Quit all mail-enabled applications, and then use the Inbox Repair Tool.
Note The file path specified in the message may vary depending upon the operating system you are using on your computer.
In addition, you might be able to open folders in the .ost but get synchronization error messages that do not go away. This happens when a single e-mail message is damaged and the synchronization process cannot correct it. You can use the OST Integrity Tool to fix damaged messages or to move them so you can synchronize successfully.
Important: You may need to run scanpst.exe (see the first procedure above) first if the OST Integrity Tool cannot open the .ost file.
To scan and repair the .ost file
1. Close Outlook.
2. On the Start menu, click Run.
3. In the Open box, type
drive:\Program Files\Common Files\System\Mapi\LocaleID\scanost.exe
where LocaleID is the locale identifier (LCID) for your installation of Microsoft Office. For example, the LCID for English (United States) is 1033. For a list of LCIDs, see Microsoft Office Help.
4. Click OK.
5. Click either Scan all folders or Choose folder to scan. If you click Scan all folders, this may take several minutes.
6. Select the Repair errors check box.
7. Click Begin Scan.
Details of actions performed during the scan and repair are saved as a message in your Outlook Deleted Items folder with the subject "OST Integrity Check."
If the Offline Folder file cannot be repaired, you can disable it and create a new one.
To disable the .ost file and create a new one
1. On the Tools menu, click E-mail Accounts, click View or change existing e-mail accounts, and then click Next.
2. In the list, click Microsoft Exchange Server, and then click Change.
3. Click More Settings.
4. Click the Advanced tab, and then click Offline Folder File Settings.
5. Click Disable Offline Use.
6. In the File box, type the path to the file you want to use as the new .ost file. The default file name is outlook.ost. If this file name already exists, you are prompted for a new name.