Cannot create index

Hi,

I have the table called actions, that contains the column "date" of
type timestamp. When I try to create the index on this column I
receive error:

pqReadData(): -- backend closed the channel unexpectedly.
This probably means the backend terminated abnormally
before or while processing the request.

I use Postgres 6.5.3 on RedHat 6.1 (kernel 2.2.13). The command I use
to cretate index is:

create index actions_date on actions using btree (date datetime_ops);

Why this happens?

Alex