I have tried to find an answer for this problem, and although I found similar questions and suggested answers in different groups (even from the Microsoft Office site), I don't have a solution yet. Here is my best shot at describing the problem:
I use Outlook 2007 and Vista. The To-do bar does not show the tasks portion, only an error message in its place: "The operation failed. An object could not be found". This has been the case for a while, no matter if I restart the program or the computer. The To-do bar shows the calendar and appointments, which I like, but the problem is with the tasks. Also, when I go to the Calendar folder, the "daily task list" (which I have checked to show in the view options) does not show, and instead the same error message appears. Otherwise email, calendar, contacts and notes work fine.
When I go to the Tasks folder, on the panel to the left, under "My Tasks" I see two groups: "To-do list" and "Tasks". Every time I go to the Tasks folder the program goes by default to the "To-do list" group, and I don't see any item, only an error message that says "Cannot display the folder". When I click on the next group "Tasks", then all tasks that I have show up, but still they do not show in the To-do bar or in the Calendar view.
I found in the Microsoft side a suggested "workaround" to right-click the personal folder, click Properties, click to select the Display reminders and tasks from this folder in the To-Do Bar check box, and then click OK. I found that this check box was already checked, therefore it did not help my case.
Here is another piece in case it helps in diagnosing the problem--I do not know whether this is something important or not: When trying to figure out a way to solve the problem I found in the Tasks folder, on the left panel under 'All task items" (a search tool) that when I click on the arrow head next to it, it lists "personal folders" twice, but only one is selected by default. Not sure why it has 2 entries for personal folders, but I have tried clicking both as well and the problem still persists.
I would very much like to have the To-do bar work fine. Thank you for your help.