problem with pg_statistic_relid_att_index

Hi,

I seem to have a problem on one of my databases,

When I log into pgsql I see this:

ERROR: Invalid page header in block 3 of pg_statistic_relid_att_index
Welcome to psql 7.3.4, the PostgreSQL interactive terminal.

When I try to run any command (eg vacuum) I get this message:

dbname=> vacuum full;
ERROR: current transaction is aborted, queries ignored until end of
transaction block

reindex also does not work:

dbname=> reindex index pg_statistic_relid_att_index;
ERROR: current transaction is aborted, queries ignored until end of
transaction block

Please can somebody help if you know how to fix this.