What could cause total crash of a postgres installation?

Hi,

Since about three days I am having strange problems with my postgresl
installation. Today in the morning at about 2am the database crashed
completely. I had the postmaster running at debug level 2 but no hint
can be found in the log. The server seemed to crash without notice.

2002-11-29 02:39:01 [3294]   DEBUG:  StartTransactionCommand
2002-11-29 02:39:01 [3294]   DEBUG:  query: select preface as
preface_txt,abstract as abstract_txt,display_type,section_auto_
numbering,lr_book_revision_id as revision_id from lr_books where
lr_book_revision_id = '115876';
2002-11-29 02:39:01 [3294]   DEBUG:  ProcessQuery
2002-11-29 02:39:01 [3294]   DEBUG:  CommitTransactionCommand
2002-11-29 02:39:01 [3294]   DEBUG:  QUERY STATISTICS
! system usage stats:
!       0.001286 elapsed 0.000000 user 0.000000 system sec
!       [456.870000 user 12.170000 sys total]
!       0/0 [0/0] filesystem blocks in/out
!       0/0 [57092/25680] page faults/reclaims, 0 [0] swaps
!       0 [0] signals rcvd, 0/0 [0/0] messages rcvd/sent
!       0/0 [0/0] voluntary/involuntary context switches
! postgres usage stats:
!       Shared blocks:          0 read,          0 written, <- last
entry

At that time more or less nothing was going on in the system. I was
already collection all kinds of log information, but I can find nothing
unusual. I could start the database with no problems.

What kind of problems could cause such a crash? Could bad memory
settings (sort, buffers) cause something like that? What kind of server
statistics should I look at?

Many TIA,

peter