You are facilitating a root cause analysis. Problem statement: {{problem_statement}}
Known facts and timeline: {{known_facts}}

Using the five-whys method:
1. Ask "why" iteratively (up to 5 times), grounded only in the facts given -- if a "why" answer would require information not provided, say what's missing instead of guessing.
2. State the most likely root cause(s) once the chain is grounded in a systemic/process cause rather than a one-off human action.
3. Propose 1-3 corrective actions that address the root cause, not just the symptom.
4. Note any contributing factor that isn't the root cause but still worth fixing.