In my experiences with groups during my time at Illinois the best examples, both good and bad, come from my work experiences.
My example of a bad group interaction comes from my first semester working as a Resident Advisor for University Housing. My original supervisor hired a staff that she felt would mesh well with her personality, and working style. The staff at the time consisted of individuals who were very laid back, and social. We got along very well with each other and things looked like they would turn out great. Although, during the summer right before we were schedule to begin work our supervisor left the university and was replaced by a new supervisor that had a completely different style. The new supervisor, was rigid, demanding, and inconsistent. Immediately the staff and the new supervisor clashed. Tempers flared, threats were issued and one of the staff members was eventually fired, which lead to a further breakdown in the relationship. Eventually, everything came to head after an email altercation between the supervisor and a senior resident advisor was forwarded to a housing administrator. An administrator was brought in to facilitate/moderate an emergency intervention between the staff and the supervisor which required a complete overhaul of our standards and practices.
The root cause of the dispute was essential a complete difference of personality, the new supervisor inherited a staff that was design for someone else. Some of issues that resulted included, supervisor bashing session between staff members, public insubordination and disciplinary action.
My example of a good group interaction comes from my time working for the Division of Campus Recreation. There the company culture is rich, and inviting. The office environment is very informal and my department felt more like a team. Everyone has set roles but we all work together to accomplish our goals and provide a great service for our patrons. Also, due to the close interpersonal relationships conflicts are few and far in-between and each member of the team is personally invested in the success of others. One of the worst things that can happen is that you disappoint your supervisor or coworker, and it feels almost like a family.
The environment that Campus Rec supports is what really helps lay the ground work for how relationships form within and between departments. On top of that because members in my department work so closely together and success depends on overall group performance, conflict can be very costly, and detrimental to the success of the group. This creates a perfect situation for coworkers to form close interpersonal bonds and to work well together.