Error Message:

Either the specified user account is already a member of the specified group, or the specified group cannot be deleted because it contains a member.

Explanation:

An application has requested a change to the security accounts database that could not be carried out.

User Action:

If the account is already a member of the group, there is no need to retry this. If the group cannot be deleted because it contains members, delete all members from the group and then retry.