BUG #1745: Unable to delete data from the database

The following bug has been logged online:

Bug reference: 1745
Logged by: K.G.Sivaraman
Email address: ksivaram(at)ssd(dot)usa(dot)alcatel(dot)com
PostgreSQL version: 8.0
Operating system: Solaris
Description: Unable to delete data from the database
Details:

When try to delete the existing name in the database (having ID and Name as
the table parameters and both are indexed), it returns success.
But when queried again, then the deleted name appeared.
When we analysed the problem, the basic delete
command itself not working.
Normally DELETE command will return the number of records deleted (ex)
DELETE 1 for 1 record.
But now, it returns DELETE 0, even though the
record is there and it is not got deleted.

The error in the log file is as follows :

ERROR : xlog flush request 0/D17B00 is not satisfied --- flushed only to
0/C31ED0
CONTEXT : writing block 0 of relation 17231/17232/17249
WARNING : could not write block 0 of 17231/17232/17249
DETAIL : Multiple failures --- write error may be
permanent.

But when I add a new record, it is getting added and
I am able to delete the newly added record.

Why this error coming ?. Can some one can help ?.