pg 8.4 crashing.

I've got a problem with pg 8.4.4 crashing with a sig 6 abort due to a
panic on failing to add a right sibling in an index. Log output:

PANIC: failed to add item to the right sibling in index "logged_in_uid"
STATEMENT: INSERT INTO logged_in ...

Now, the column that's failing here is a serial that isn't referenced
in the SQL statement, i.e. it gets the default nextval.

OS: Ubuntu 8.04,
Pg: 8.4.4 The only arg to ./configure was to change the prefix dir to ~/pg84

I've had this problem before, but didn't have the time to track it
down. Now I do, and it's on a server I can play on a bit if I need
to.

--
To understand recursion, one must first understand recursion.