Project Tasks hidding normal tasks in Daily Task List

Hi everybody!

I just noticed the following bug that is driving me crazy.
If I create a Project Task and then a regular Outlook task both with the same Due Date then in the To-Do View I can see both of them right, but in the Calendar's Daily Task List pane I only see the Project Task.. The normal task is not there!..

I wonder, am I doing something wrong or is this indeed a bug?

I should also mention the following:
1. Both tasks (the Project Task & the regular Outlook Task) span across multiple days but both have the same due date.
2. If I create a second regular Task then this gets displayed correctly in the Calendar's Daily Task List. (..while the first regular Task is still hidden..)
3. I also noticed that in an other due day where I have multiple regular Tasks and one Project Task all of them are displayed correctly!?!?...
4. The due date I noticed the problem is Sunday, while the other due date that is working fine is a working week day (Friday).

I can't figure out the pattern that this bug occurs..
I also heard that similar problems occur with Project Tasks when working with Outlook & Project Server 2007 but I cannot verify these.

Any info or confirmation of this behavior would be much appreciated.

Thanks in advance,
Mary P.