User Notification Problem

I set up a user notification in Integrity to notify me when a defect or change request has been assigned to me.  It looks like this:

This works well except there seem to be a trigger that runs overnight that updates all of the Defects and Change Requests that are in the system.  When I look in my email every morning, there is a notification for every defect and change request that was ever assigned to me.

Is there something that I should change in my notification that would prevent this.  Also, I tried to exclude these items by using the user = -system- value but it did  not work.

Any help would be appreciated.

Happy New Year!

Ginny M.