I have created a custom permission level (it basically the Countribute permission minus DELETE) where a user can ADD/EDIT items but not DELETE items. if the user tries to change the "Name" field and try to save the properties it throws an "Access Denied" message. the user can edit other fields and save the changes but if he tries to update the "Name" field is thrown an "Access Denied" further if I update the permission level to include "Delete" he can modify the "Name" field. Appreciate your responses Thanks

Yes... modifying the name of the file is consider by the system as a delete so users need to have delete access on the item... Windows have the same behavior (you need delete access to rename a file in windows)