input in flex scanner failed

Hi,
I have about 35 servers running Postgresql. On one of my older ones, which just
serves up old data with no new data being added,
and running on redhat 7.3 with postgresql 7.2.4, I am getting repeated episodes
of the database shutdown while the system is still up. I find this very
unusual.

When I log in to the machine and I run pg_ctl start I get the message
input in flex scanner failed
and the Postgresql database system does not start up. :(.

I suppose, I should just do my work and reinstall linux - debian and the latest
postgresql - but does anyone know what this error means before I blow the
machine away?

Thanks for all your help,
Mitchell Laks