Server closed the connection unexpectedly

I'm getting the following when running a Select statement

"dbadmin=> \i queries/Query1.sql
vsql:queries/Query1.sql:49: server closed the connection unexpectedly        This probably means the server terminated abnormally        before or while processing the request.
vsql:queries/Query1.sql:49: connection to server was lost"

Although the Management Centre still reports that the nodes are all up, and the database is live, running admin tools reports that the node on which vsql was running is down. So running this query kills the node. Using AdminTools on the node to restart it 'Restart Vertica on Host' fails to restart the node. So far, I'm still working out how to get that node up again.

Clearly, when simple SQL Select statements bring down nodes, it's very concerning. It's also concerning that the two different tools AdminTools, and Management Console offer 2 different opinions on whether the node is up (Management Console seems particularly confused as whilst it has Node 1 as up, it has Nodes 2,3,4 as critical - but if Node 1 is up, they wouldn't be I'd think).

Our Vertica version is 6.1.2, we have the EE licence, and a 4 Node cluster running Xeon-E5 2670 processors.

I can't paste the query here, but line 49 is the last line of the query. The query does a little simple math, a few joins, has a where clause.

I don't expect a resolution, but I would like some suggestions on how to go about investigating the cause and resolving it myself.

Thanks,

Neil