PANIC : right sibling's left-link doesn't match

[resend w/ plain text only - Sorry]

right sibling's left-link doesn't match: block 121425 links to 124561
instead of expected 121828 in index
Oct 20 22:21:29 hmweb5 postgres[8795]: [3-2]  "d_trh_trr_water_eval_pkey"

WARNING:  terminating connection because of crash of another server process
DETAIL:  The postmaster has commanded this server process to roll back the
current transaction and exit, because
WARNING:  terminating connection because of crash of another server process

What does the above mean?

This is causing DB to have bad reactions.

Thanks.

Is there an index error? Should I drop and re-create the index is it?