Delegate permissions disappear

[JCLandisJr]

Here is what we are currently running:

Win2k domain - mixed mode
Exchange 2k - navtive mode

Our issue is that we will add a delegate and give that person permissions to
view, edit, etc...

Then overnight these permissions disappear along with the default user.

When the delegates then try and view the person's calendar, they cannot.

We will then put the default user back and redo the user's permissions.

Then within a few days the permissions will disappear once again.

Any help would be appreciated.