This is known issue and EMC engineering team is working on it.

In networker 7.4.2 jobsdb is behaving unlikely and loosing connections.

As said earlier rename jobsdb folder and try again which would resolve 
issue but you would need to start schedule backup jobs manually once so 
that from next time onwards it will run automatically.

To sign off this list, send email to listserv AT listserv.temple DOT edu and 
type "signoff networker" in the body of the email. Please write to 
networker-request AT listserv.temple DOT edu if you have any problems with this 
list. You can access the archives at 
http://listserv.temple.edu/archives/networker.html or
via RSS at http://listserv.temple.edu/cgi-bin/wa?RSS&L=NETWORKER