This map is failing because it is exceeding the file size limit set within ArcGIS.
In practice, it is generally recommended that any kind of segment LDU map is created for a much smaller geographic area than a CMA. From a visualization perspective, it is very hard to glean any meaningful insights from a CMA segment LDU map. In the attached map below (Screen Capture 1), all the target group segment dots become muddled together and you're only able to see the top layer of segment dots (red in this case), there could be many more green, yellow and purple dots underneath those red dots but you would never know it. The map would be more effective for analytical purposes if a single CMA map was broken out into several LDU maps or, if a map of the entire CMA is a requirement, then it would be better to create this map in a PRIZM5 DA workspace (Screen Capture 2), not a Postal Code workspace.
Screen Capture 1
Screen Capture 2