Problem:A Notes 5.x customer receives the following error when attempting to access the preferences file via Tools, Preferences in their mail file:"Type mismatch on external name: DELEGATIONACLMANAGER".Solution:To address this issue, delete the Script library "ACLManagement" and do a Replace, Design with the MAIL50.NTF template.Supporting Information:Additionally, it should be noted that one customer has seen this problem solved by simply deleting the CACHE.DSK at the workstation.This issue was reported to Lotus Quality Engineering; however, it has not been reproducible.