Problem in creating an INDEX

I have a table that I used to have a working index. It seemed to fail
so I removed the index and tried to recreate it. I am now receiving errors
when building the index:

stocks=# select count(*) from history ;
count
---------
3882589
(1 row)

stocks=# CREATE INDEX ihisidda on history (hisid, hiday) ;
ERROR: ltsReadBlock: failed to read block 7960 of temporary file

I dont believe it is a disk problem as I moved the database onto a different
disk and I still get errors. Any ideas on what could be the problem.

--
Daryl Sayers
Corinthian Engineering Ph: (02) 9906 7866
Suite 19, 401 Pacific Hwy Fax: (02) 9906 1556
Artarmon, NSW, 2064 email: daryl(at)ci(dot)com(dot)au
Australia www: http://www.cordoors.com.au