Cannot read block error.

I am running PostgreSQL 7.3.3 on OS X Server 10.2

The database has been running just fine for quite some time now, but
this morning it began pitching the error:
ERROR: cannot read block 176 of tfxtrade_details: Numerical result
out of range
any time the table tfxtrade_details is accessed.

A description of the table is at the end of this email

I have a backup from last night, so I haven't lost much data (if any),
but I am curious if there is a way to recover from this (beyond
restoring from backup) and how I would go about figuring out what
caused it to prevent it from happening again.

I will keep a copy of the data directory if anyone wants me to do any
analysis on it (I will need instructions).

Any insights would be appreciated.

Thanks

Jason Essington
jaessing(at)greenrivercomputing(dot)com

hedgehog=# \d tfxtrade_details
Table "public.tfxtrade_details"
Column | Type | Modifiers
---------------+--------------------------+-----------
rid | integer | not null
clientid | integer |
tradeid | integer |
rollid | integer |
rollpct | numeric(10,8) |
expdetailid | integer |
expid | integer |
contractpct | numeric(10,8) |
contractamt | numeric(18,2) |
origpct | numeric(10,8) |
origamt | numeric(18,2) |
acctgperiod | integer |
acctgperiodid | integer |
editdate | timestamp with time zone |
edituserid | character varying(48) |
parentid | integer |
entityid | integer |
tradedate | date |
maturitydate | date |
strategyid | integer |
currencyid | integer |
Indexes: tfxtrade_details_pkey primary key btree (rid),
tfxlinks_entityid_index btree (entityid),
tfxlinks_expdetailid_index btree (expdetailid),
tfxlinks_expid_index btree (expid),
tfxlinks_mdate_index btree (maturitydate),
tfxlinks_parentid_index btree (parentid),
tfxlinks_strategy_index btree (strategyid),
tfxlinks_tradeid_index btree (tradeid)
Triggers: RI_ConstraintTrigger_30891,
RI_ConstraintTrigger_30894,
tfxdetail_delete_trigger