The success of information systems (IS) and especially knowledge management systems (KMS) is defined through the acceptance and usage of them. Directly after the implementation the initial success of such systems starts with a relatively good acceptance and usage. When the first hype is over the problems of the systems become evident and the acceptance and usage dwindles. But what kinds of problems lead to the decreasing acceptance and finally to the rejection of the system? Our research in progress approach is intended to investigate those reasons for changes in the beliefs, attitudes and satisfaction of KMS users. Therefore one longitudinal case study is conducted in the financial services industry. The main objective is to elucidate inhibitors and enablers of KMS usage over time. The first period of investigation will be conducted before the implementation of a new KMS replacing an old one implemented in 1999 which has been identified as a major reason for a declining job satisfaction within the organization observed. The second period of investigation is directly after the implementation and the third one after at least one year thereafter. Within our research-in-progress article we describe the theoretical background and research setting of our approach and present first results of the first data collection period.