You need to delete the .NK2 file
Windows Vista
If you can already see hidden files and folders...
1. Close Outlook.
2. Open My Computer.
3. Browse to C:\Users\<username>\AppData\Roaming\Microsoft\Outlook
4. Make sure to view the file details.
5. Delete any file that ends with “.NK2â€.
6. Restart Outlook and the new NK2 file will automatically rebuild.
If you cannot see hidden files and folders...
1. Click the round Windows Start logo in the bottom left corner
2. Select Control Panel
3. Click Organize
4. Click Folder and Search Options
5. Click the View tab
6. Check Show hidden files and folders
7. Click Apply then OK
Windows XP
If you can already see hidden files and folders...
1. Close Outlook.
2. Open My Computer.
3. Browse to C:\Documents and Settings\[logged in user]\Application Data\
Microsoft\Outlook.
4. Make sure to view the file details.
5. Delete any file that ends with “.NK2â€.
6. Restart Outlook and the new NK2 file will automatically rebuild.
If you cannot see hidden files and folders...
By default you will not be able to see the below directories unless you make
a couple of adjustments.
1. To view hidden folders, open My Computer
2. Tools > Folder Options
3. Click the View Tab
4. Select “Show hidden files and foldersâ€.
5. Then UNCHECK the box that says “Hide extensions for known file typesâ€
6. Click “Apply to ALL Folders†button hit OK. (proceed to the steps in the
previous section)