VACUUM is hanging

Maybe someone will know what's going on here.

I'm running 7.1 and vacuuming the db regularly at 4am each day. But
these last few days as it vacuums it hangs reaping dead processes.

2001-05-04 04:00:09 [27285]  DEBUG:  --Relation personnel--
2001-05-04 04:00:09 [27285]  DEBUG:  Pages 0: Changed 0, reaped 0, Empty 0, New 0; Tup 0: Vac 0, Keep/VTL 0/0, Crash 0,
UnUsed0, MinLen 0, MaxLen 0; Re-using: Free/Avail. Space 0/0; EndEmpty/Avail. Pages 0/0. CPU 0.00s/0.00u sec. 
2001-05-04 04:00:09 [27285]  DEBUG:  Index personnel_pkey: Pages 1; Tuples 0. CPU 0.00s/0.00u sec.
2001-05-04 04:00:09 [27285]  DEBUG:  Index personnel_name: Pages 1; Tuples 0. CPU 0.00s/0.00u sec.
2001-05-04 04:00:09 [27285]  DEBUG:  Index personnel_truck: Pages 1; Tuples 0. CPU 0.00s/0.00u sec.
2001-05-04 04:00:09 [27285]  DEBUG:  Index personnel_ssn: Pages 1; Tuples 0. CPU 0.00s/0.00u sec.
2001-05-04 04:00:09 [27285]  DEBUG:  Analyzing...
/usr/lib/postgresql/bin/postmaster: reaping dead processes...
/usr/lib/postgresql/bin/postmaster: CleanupProc: pid 27299 exited with status 0
/usr/lib/postgresql/bin/postmaster: reaping dead processes...

Then there are hundreds of the last three lines until I get here the
next morning and try to access the database, that then seems to give it
a kick in the pants, for a while at least, then it returns to its
inane suicide ritual. Any ideas?

Restarting the DB and running a vacuum by hand in psql works, but I
don't know if it will clog up tonight or not...

--
really hacks