Data Corruption?

Hello,

After about a year and a half of use, I ran into a peculiar problem
with my PostgreSQL driven app and I would like to understand why.

I have a web app that uses PostgreSQL 6.5.2 on the backend. The app logic
is Java beans and JSP. The OS is RedHat 6.2 i386. Anyways, there are two
identical databases that are simultaneously accessed by the application
for any type of data transaction, for redundancy purposes.

Last month, I started getting various inexplicable error messages both
with the web app and with psql. The most incriminating were these two:

ERROR: carcustomer: Table does not exist

~and~

FATAL 1: Memory exhausted in AllocSetAlloc()

In psql, for example, simple queries would hang for awhile and then
produce the memory error message.

After doing some troubleshooting, I dropped the table that seemed to be at
least in part the culprit, the "car" table, and then replaced it with a
dump of the same table from the secondary mirror database. At that point,
the error messages ceased and everything has worked great for the last 3
weeks.

Now I need to understand why this happened so I can address it properly.

Does anybody know what may have caused this?

Thank you,

-Robin