It maybe necessary to create a Change in order to apply the permanent fix for the Problem.
Raising a Linked Change
From the Problem record it is possible to raise a linked Change. This will promote up the important information pertaining to the Problem into the Change record and also automatically create a linked relationship between the new Change and the existing Problem.
Using the Business Process Designer it is also possible on the resolution of the Problem to automatically cascade an update down to the linked Incidents to let them know the Problem has been fixed.