As part of its public sector modernization effort, a North African government has put a lot of effort and allocated significant budgets since 1997 to modernize one of its main public sector companies. Consequently, this company, that mainly offers postal services, initiated many IT-based projects to computerize all paper-based ongoing services offered through its branches and to present new products to customers. This company was aiming to improve service quality and to diversify the range of its services. However, some of these IT-based projects inevitably faced problems. Some projects were either not completed successfully, cancelled, over-budget or taking more time than scheduled. As a result, many employees and customers of this company were dissatisfied and complained about bad planning, slowness and significant disruptions in these projects, an event that affected adversely the quality of service. This study aims at determining the causes of these project disruptions, failures or delays. To achieve this aim, 30 experienced project developers and engineers working in that company's IT department volunteered to respond to a detailed questionnaire specifically developed for this purpose. The questionnaire included questions about project vision clarity, time/cost management, project quality assurance, risk management and human resources management. Results show that the main reasons for disruptions, failure or delays in IT projects are lack of business plan and poor documentation during and after finishing projects, lack of clear quality assurance criteria, standards and reviews, and poor project risk management practices. Ramifications of such results in terms of improving IT project management practices in the public service sector are finally presented.