exit code 128

Today I postgres on one of our servers shutdown with exit code 128.
Postgresql 8.3.7 on Windows 2003 server.

It started up normally but this is the second occurance this week.
Below is a section of the log. A restart of the service returned
postgres to normal. Suggestions?

Thanks,
Roger

2009-04-06 10:47:15 HST LOG: automatic vacuum of table
"crm.quartz.qrtz_triggers": index scans: 1
pages: 0 removed, 5 remain
tuples: 58 removed, 14 remain
system usage: CPU 0.00s/0.01u sec elapsed 0.06 sec
2009-04-06 10:47:15 HST LOG: automatic vacuum of table
"crm.pg_toast.pg_toast_63861": index scans: 0
pages: 0 removed, 0 remain
tuples: 0 removed, 0 remain
system usage: CPU 0.00s/0.00u sec elapsed 0.00 sec
2009-04-06 10:47:15 HST LOG: automatic analyze of table
"crm.quartz.qrtz_triggers" system usage: CPU 0.00s/0.01u sec elapsed
0.04 sec
2009-04-06 10:48:11 HST LOG: server process (PID 4912) exited with
exit code 128
2009-04-06 10:48:11 HST LOG: terminating any other active server
processes
2009-04-06 10:48:11 HST WARNING: terminating connection because of
crash of another server process
2009-04-06 10:48:11 HST DETAIL: The postmaster has commanded this
server process to roll back the current transaction and exit, because
another server process exited abnormally and possibly corrupted shared
memory.
2009-04-06 10:48:11 HST HINT: In a moment you should be able to
reconnect to the database and repeat your command.
2009-04-06 10:48:11 HST WARNING: terminating connection because of
crash of another server process
2009-04-06 10:48:11 HST DETAIL: The postmaster has commanded this
server process to roll back the current transaction and exit, because
another server process exited abnormally and possibly corrupted shared
memory.
2009-04-06 10:48:11 HST HINT: In a moment you should be able to
reconnect to the database and repeat your command.
2009-04-06 10:48:11 HST WARNING: terminating connection because of
crash of another server process