Dê uma olhada aqui: Analise e repare arquivos de dados corrompidos do Outlook
Crie uma cópia do arquivo pst antes de tentar repará-lo.
Para arquivos PST
Scanpst.exe is installed when you install Outlook. It is located at:
drive:\Program Files\Microsoft Office\OFFICE12.Exit Outlook if it is running.
Double-click Scanpst.exe, located at drive:\Program Files\Microsoft Office\OFFICE12.
In the Enter the name of the file you want to scan box, enter the name of the .pst or .ost file that you want to check, or click Browse to search for the file.
To specify the scan log options, click Options, and then click the option that you want.
Click Start.
If errors are found after the scan is complete, you will be prompted to start the repair process to fix the errors.A backup file is created during the repair process. To change the default name or location of this backup file, in the Enter name of backup file box, enter a new name, or click Browse to look for the file that you want to use.
Click Repair.
Start Outlook by using the profile that contains the .pst file that you tried to repair.
On the Go menu, click Folder List.In the Folder List, you may see a folder named Recovered Personal Folders that contains your default Outlook folders or a Lost and Found folder. The recovered folders are usually empty, because this is a rebuilt .pst file. The Lost and Found folder contains the folders and items recovered by the Inbox Repair tool. Items that are missing from the Lost and Found folder cannot be repaired.
If you see a Recovered Personal Folders folder, you can create a new .pst file, and drag the items in the Lost and Found folder into the new .pst file. When you have finished moving all the items, you can remove the Recovered Personal Folders (.pst) file, including the Lost and Found folder, from your profile.
Para arquivos OST
The OST Integrity Check tool (Scanost.exe) is installed when you install Outlook. It is located at:
drive:\Program Files\Microsoft Office\OFFICE12. Repair errors by using Scanost.exe
Exit Outlook if it is running.
Double-click Scanost.exe, located at drive:\Program Files\Microsoft Office\OFFICE12. If you have set up Outlook to prompt for a profile, the tool will also prompt you for one. In the Profile Name list, click the profile that contains the .ost file that you want to check.If you are prompted to Connect or Work Offline, click Connect.
Select the options that you want.
To have the tool automatically resolve discrepancies that it finds during the scan, select the Repair Errors check box. If this check box is cleared, the tool will log the problems but not make the necessary corrections.
Click Begin Scan.