Write errors in postgres log

Hello,

We have 2 servers running postgres database 8.0.3 serving a web application.
Recently, we started having problems with the web application and diagnosis
lead to the following errors repeated in the postgres log files on both the
servers.

==========================================
CONTEXT: writing block 754 of relation 1663/17230/17443
WARNING: could not write block 754 of 1663/17230/17443
DETAIL: Multiple failures --- write error may be permanent.
ERROR: xlog flush request 2/66B19020 is not satisfied --- flushed only to
2/5F8F95A2 ...
===========================================

Both the servers are running independently and geographically apart. We
don't think there is anything wrong with the hardware and this error seem to
get worse and worse over time.

Trying to recover from the error,

1. pg_reset_xlog did not work.
2. Recent backups are corrupted as well.

Any advice to recover and pin point the cause of the error will be
appreciated.

Thanks in advance