I have added two domain users to a Win2008 server (non-domain controller) as local administrators. However these two users still have very limited rights, such as not being able to modify local Internet Security Properties. Is there another setting overriding their local admin permissions that they are supposed to have?
Make sure you're "elevating" before doing anything that requires administrative rights. Being a member of the local administrators group means that when you get prompted, it's just to click "Ok" vs. having to provide a separate user name and password.