Have you tried running Detect & Repair feature available under the Help menu
in Outlook to scan the pst file. Additionally, you can also try running the
Scanpst utility to check for any corruption in the PST file (the file that
stores your Outlook data). Search for scanpst.exe on your computer.
You will need to run it against the .pst file. If you are unable to locate
the path of the .pst file, do the following:
1. Open Outlook.
2. Click File -> Data File Management
3. This should list all the PST files that are present. Click Open Folder
and you should find the storage path of your *.pst file.
Microsoft MVP - Mobile Devices