Here's what I do and what eventually happens:

1. Add a task to Microsoft Outlook and don't assign a date
2. Sync my phone to Outlook using Blackberry Desktop Manager
3. View my tasks on the phone - no date appears.
4. The next day I sync my phone. Before syncing I verify that no date was assigned in either Outlook or on the BB
5. When I sync, tasks on my phone attempt to add a task date to Outlook.

If this not's weird enough, when I go to look at the task on the phone, I confirm that a date hasn't been assigned. However, the dates trying to be assigned are puzzling ... 11/4/2483, 9/26/2410, 7/9/2478, etc.

This phone has never ever liked Outlook tasks that don't have a due date assigned.

I'm experiencing the same problem. I discovered a workaround in another forum "somewhere" ;-} the following:

The solution:

Blackberry Desktop Manager -> Synchronize -> Configuration tab -> Config synch... -> Tasks -> Configure -> Advanced Settings... -> Field Mapping: Now set the handheld "Start date" to NOT synchronize.

Why does this solve the problem?

On the blackberry, tasks don't have a start date. My guess is that Intellisync is finding a number it thinks is a start date, and that number is being converted into a strange start date in Outlook. In Outlook, whenever a start date is AFTER the due date, the due date is set to be the same as the start date.

This is frustrating, because all RIM needs to do to fix this problem is change the default field mapping.

Just joined BlackBerry Forums. Have had a BB Pearl for almost a year, and really like it despite its flaws. Had the exact same problem dalehouser described above. Followed rachris2's advice and the frustrating problem was solved. Thanks.