A logical way for proceeding with the resolution of an issue could be as follows:
Record the non-conformance, identify any specific measures that must be taken immediately to, for instance, stop the product from going out. Then initiate the investigation process to identify the Root Cause. If it is a single occurrence issue with little risk then it is possible that the process can stop there although there must be a process for ensuring that the problem does not get repeated.
For more important issues and particularly those presenting a risk to the business then the process should be escalated to that of a formal Corrective Action. This will involve a more thorough analysis of the Root Cause and the concise identification of Corrective Measures that need to be taken. These measures should be appropriate to the severity of the problem and clear instructions and responsibility must be given to correct the problem. For a Corrective Action to be effective proof must be provided of the implementation of the measures taken to ensure that recurrence of the problem has been prevented.
Strictly speaking a Preventive Action should always accompany a Corrective Action so that there is a documented proof that measures where taken to prevent the recurrence of the problem as well as fixing the problem. There should also be a pro-active process in place to identify potential areas of non-conformance, before they occur, and to implement steps to ensure that, once identified, they do not occur. Again, clear instructions and responsibility must be assigned with proof of implementation before a formal Preventive Action is completed. Clear and concise documentation for each process, with assigned responsibility and specific deadlines ensures that the resulting changes are implemented in a time critical manner and that clear proof is available of their effectiveness.