Another postgres 'file not found' error

This is the second time within a week I've been hit by a peculiar 'file not
found' error. I've been replacing a few existing Oracle servers with
Postgres. I'm wondering if that was a wise decision :/

inbound=# update store set state = 0, timestamp = 'now' where timestamp <
(CURRENT_TIMESTAMP - interval '30 seconds') and accountid = '6';
ERROR:  cannot open segment 1 of relation store_ix1 (target block
1576985508): No such file or directory

--
Ian Cass