'SGT DETAIL: Could not open file "pg_clog/05DC": No such file or directory' - what to do now?

On 1st May, I saw this message in my postgres log:

May  2 06:52:02 db10 postgres[3590]: [29829-1] 2011-05-02 06:52:02 SGT
ERROR:  could not access status of transaction 1573786613
May  2 06:52:02 db10 postgres[3590]: [29829-2] 2011-05-02 06:52:02 SGT
DETAIL:  Could not open file "pg_clog/05DC": No such file or directory.
May  2 06:52:02 db10 postgres[3590]: [29829-3] 2011-05-02 06:52:02 SGT
STATEMENT:  SELECT 1 FROM core_bill_id_seq FOR UPDATE


Now, I'm not sure what I should do about it. Database behaves "funny",
some inserts do not work.


Searching the internet suggests that:

1) such errors could happen with PostgreSQL 8.1.x under heavy load -
this server is under constant heavy load, but runs 8.3.14 on Debian Lenny

2) I should simply create a 256k pg_clog/05DC empty file with dd - I
wouldn't like to do it, without first knowing what happened, and if it's
really "good fix"

3) some tables can be corrupted - how can I check that? pg_dump works
fine and doesn't report any errors

4) I may have hardware problems - but this server is running for almost
1 year now, is super stable - servers with hardware issues are likely to
show some issues as well

5) database corrupted due to a server crash - this server never crashed


How should I continue from that (assuming I can't reliably verify if
something wrong is going with the hardware or not - points 4 and 5)?


--
Tomasz Chmielewski
http://wpkg.org