PGSQL service dieing...

My pgsql service keeps dieing and has a bunch of errors like this in the
server log, eventually it stops giving these

Warning: terminatin connection because of crash of another server process
Detail: The postmaster has commanded this server process to roll back the
current transaction and exit, because nother server process exited
abnormally and possible corrupted shared memory
Hint: ina moment you should be able to reconnect to the database and repeat
your command

And starts giving these:

FATAL: the database system is in recovery mode

Could a series of commands, say perhaps a few hundred of the course of an
hour, that had incorrect syntax cause a problem like this? Is there
anywhere I can go for more info?

Dan