These errors in the dispatcher.log indicate that the dispacher JVM is unable to open any new sockets due to a resource limitation on the physical machine. The keyserver must be able to open new sockets on port 5609 to conduct keyserver elections. If the keyserver is unable to reach any of the other keyservers because it cannot open new sockets to conduct an election, it will assume that it is the only keyserver and it will elect itself as a master keyserver. Even though it cannot contact the other keyservers for elections (this requires a new socket) the keyserver may still generate keys and these may be provided to clients that request them. This can lead to a variety of errors.
Identify the reason for the resource limitation on the machine hosting the disptacher. Restart the machine to free up resources.
If this issue occurs frequently there may be a socket leak (typically against another application) on the same machine that is using all the resources.
Upgrade to a 64 bit JVM and add memory. This issue is rarely seen on modern systems.