Problem Based Learning offers many benefits to students' learning, however, the design and implementation of effective problem based learning (PBL) is not trivial. Central to effective implementation of PBL are the problem design and group working of the students. Design of good problems requires that the learning outcomes of the subject are covered in the problem given. Effective problems should include all learning outcomes as well as making sure that resources are available. Group working is an essential part of PBL. However, group work among students is not easy. For learning to be effective, the group must share knowledge and engage in their learning. It is vital that the group functions well and everyone takes up his or her role. In reality students often find group working difficult and they prefer to work on their own. How do we promote knowledge sharing among students? This paper describes design and group issues that need to be addressed for PBL to be effective and successful. Furthermore, it includes a case study of the implementation of learning objects in a virtual learning environment to support PBL on a final year undergraduate module in microcontroller interfacing.