Hershey, a leading chocolate manufacturer, needed to replace its legacy systems to address Y2K issues and enable more efficient operations. It implemented SAP, Siebel, and Manugistics software in a big bang approach over 30 months. However, the system went live during their busiest season, and they were unable to fulfill Halloween orders, which significantly hurt sales and profits. Key lessons learned were that enterprise software requires business process change, adequate testing is needed, and careful timing of go-live is important. After upgrades and improvements, Hershey now has near 99.96% inventory accuracy and can fulfill orders within 24-48 hours.