URGENT - HELP WITH 7.3.4 Strangeness

I am in need of some help.

We are experiencing a lot of very weird strangeness with our Postgresql
databases.  It appears that we are suddenly suffering from a lot of
possible index corruption or other db problems.

Here is what is happening:

1.  Last Sunday, ran a reindex on all databases across our 3 postgresql
servers.  This was done using the reindexdb script from the contrib
directory.  The reindex was prompted due to strangeness on  db server 1.

2.  Wednesday, our application suddenly starts having data issues.  It
issues selects to db and does not display the rows.  Nothing on the
application has changed.  This is happening across all 3 database
servers.  (App runs on Windows and connects via a linux "app" server
using linux odbc (from gborg.postgresql.org) to connect to postgres.

3.  Pulling queries from db logs and running them via psql returns rows.

4.  Wednesday night.  Moved all db's from initial problem database
server to new db server.  Moved another problem db to new server.  New
db's run fine.

5.  Wednesday night.  Dumped and reloaded several problem db's on
problem servers 2 and 3.

6.  Thursday was relatively quiet.

7.  Friday, problems reappeared on servers 2 and 3.

8.  Friday night.  Shutdown, powered off db servers 2 and 3.  Ran fsck
on all drives.  Ran reindexdb across all db's and vacuum analyzed.

9.  Saturday morning - life is good.

10.  Sunday night, check db's to verify things are good.  DB Server 2 is
exhibiting problems, db server 3 is fine.

11.  Sunday night - reboot db server 2.  Everything is fine.

12.  Monday (today). - Apparent index corruption on new db server 1.
Row in db table but query using index will not pull it.  Small database
so reindexed it.

In synopsis:

System runs fine after reboot, but appears to start having index
issues.  We are able to query the db and see the data if we force a seq
scan, but an index scan returns random results.  Nothing has changed
application or db wise.

All server Dell Poweredge 2650's
RedHat ES 2.1
Postgres 7.3.4  (with perl)
DB's on Dell PowerVaults using raid5

I really need some help solving this.  I have never seen anything like
this before.  Does anyone have any ideas?

Thanks,

Chris