This document discusses types of information systems and case studies on the failure of companies due to ineffective use of decision support systems (DSS). It outlines strategic, management, knowledge, and operational level systems and examples of sales forecasting, production scheduling, and order processing. Case studies describe how Kmart failed to implement a supply chain system like Walmart's, how Motorola was unable to launch new smartphones, and how an ERP implementation cost HP $160 million in lost revenues. Suggestions include learning from past mistakes, testing systems, and keeping systems updated to avoid failure.