TOAST table (or index?) corruption on PITR replica

We have a customer running a very high-velocity database. We have set
up a PITR replica that's restoring correctly using JD's PITRtools and
pg_standby.

However, upon stopping the recovery and starting it for production (for
"switchover") it promptly gets into these problems:

14895 2009-02-28 22:19:08 EST kangaroo app 49a9fe2e.3a2f ERROR: missing chunk number 0 for toast value 93557123
14895 2009-02-28 22:19:08 EST kangaroo app 49a9fe2e.3a2f STATEMENT: update sometable set stop_status=1, stop_time=current_timestamp, stop_method=1 where unit_id='227245' and email='foobar(at)example(dot)com'

14903 2009-02-28 22:22:02 EST kangaroo app 49a9fe2e.3a37 ERROR: index "pg_toast_42299_index" contains unexpected zero page at block 23768
14903 2009-02-28 22:22:02 EST kangaroo app 49a9fe2e.3a37 HINT: Please REINDEX it.

There were actually several different instances of the first error
involving different toast values.

The servers are running 8.3.5.

Does this ring a bell for anyone?

--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.