Are you using IPV6?
I had a similar issue with Splunk 6.0 build 182037. "ERROR TcpChannel - Error trying to begin socket accept: An invalid argument was supplied."
I pinged the Splunk Indexer and found that it was using IPV6 to resolve the hostname. I disabled IPV6, then added the hostname IPV4 address in the localhosts file. Restarted Splunk and it is working fine now.
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