Double items in Outlook 2007/2010 tasks list

When I schedule something in my Outlook calendar or a task list, the appear twice in tasks panel. If I delete one, both are deleted! What’s wrong?

This issue can be caused by problems in the ‘to-do bar’. To reset your Outlook to-do bar to the default configuration:

1. Click ‘Start’
2. Click ‘Run’
3. Type: outlook.exe /resettodobar

Outlook will launch with your to-do bar re-configured. You may then close and re-open Outlook normally.

Note: Many users experience this issue after opening an Outlook 2003 or 2007 version PST file in Outlook 2010.