This paper describes research into problems commonly experienced when implementing an off-the-shelf information system into the complex work-practices of an organisation. Encountering such an occurrence, the authors employed a grounded theory approach to study the case though the collection, analysis and interpretation of a variety of data. The case concerned the troubled introduction, into a large educational institution, of a complex class timetabling system that was already well established in another similar organisations. Unanticipated problems encountered by various stakeholders in the system during and following the implementation of the system are documented and classified into three categories: knowledge issues, system issues, and organisational issues. Aspects of these categories are analysed for this particular case and then generalised to provide lessons for those in any similar situation.