Kernel panic error

Hi,

I have been using Postgres 7.0.3 for the last few weeks. I also use LVM on
the 2.4 kernel. I have very large tables (one of which is over 2GB).

My problem is that lately (the last week), when doing maintenance (normally
at night using a cronjob), the follwoing error has been repeatly given:

Incorrect number of segments after building list
nr_segments is 8
counted segments is 2
Flag 1 0
Segement 0xc5fa74a0, blocks 8, addr 0x4007ffff
Kernel panic: Thats all folks. Too dangerous to continue.

I have noticed yesterday that postgres gave the error below before the
kernel panic. This error was given when vacuuming one of the smallest
tables in the database.
Error index_formtuple: data takes 21268 bytes: too big

Anyone has any ideas what is happening ?

Thanks
Robert