Self reference exception thrown while updating the database from the dataset

Hi, I am developing a windows based application. We are using typed data sets to store data in memory. We have a folder structure that mimics the windows explorer folder structure. ie. a folder ''f1'' has a child folder say ''f2'' which in turn has a child folder say ''f3''. When the user right clicks on folder ''f1'' and says delete, I am first deleting f3, then f2 and then f1. However when I try and save the changes to the database by calling the update method, it throws a self reference exception. My guess it that this is happening because while updating the database the record ''f1'' is getting deleted first. How can this problem be solved? Thanks, Utsav.