Strange message followed by server crash

I'm trying to figure out what exactly caused PostgreSQL to crash.

PostgreSQL 8.0.7
OS: Red Hat Linux EL 4.0

Log messages:
<1Tmenteshvili 10709 2006-08-24 17:48:19 BST 0> ERROR: invalid message format
< 3670 2006-08-24 17:48:19 BST > LOG: server process (PID 10709) was terminated by signal 11
< 3670 2006-08-24 17:48:19 BST > LOG: terminating any other active server processes

Looking into PostgreSQL code I note that the message "invalid message format" is generated by function: pq_getmsgend which is called when processing incoming messages from clients.
So am I correct in assuming that there was an error in the front end/back end data sent to PostgreSQL?

I asked the client above what they were doing when this event occurred and the answer was logging out of the database.

At the same time, an engineer, who thought nobody was in the building, was working on the network and changing a network switch.
Therefore can I assume this crash was caused by some form of corrupt / incomplete data sent to PostgreSQL?

Thanks in advance
regards
Donald Fraser