Personnel shortfalls (more resources)

Unrealistic schedules and budgets (more time, more resources)

Developing wrong software functions (requirements spec)

Developing wrong interface (requirement spec, scenario-based design)

Unnecessary perfectionism (review)

Continuous requirements changes (review)

Shortfalls in outsourced tasks (review, requirement spec)

Shortfalls in outsourced components (review, testing)

Realtime performance shortfalls (performance evaluation, more resources)

Straining computer science capabilities (performance evaluation, more resources)