We used to have it set to auto-start with TCP. Earlier this year, we encountered a problem where our system wouldn't accept any ODBC requests. IBM determined that Nav for I grabs a port at random during startup without checking if that port is actually reserved for some other service. In this case, it grabbed the port used by ODBC. IBM said that they would attempt to fix this in some future release, but in the meantime they told us to not auto-start Nav for I with TCP.