probs with 7.3 -> 7.4 on debian

Hi all
Debian has upgraded me to 7.4 ofpostgres, but when it tries to start
postgres I get an error mentioning that the data is in 7.3 format and
needs to be upgraded to 7.4 format before postmaster will start.

"dpkg-reconfigure postgresql" attempts to do just this for me, but fails
during upgrade.

so I follow the instructions in README.Debian.migration like so:

odin:~# su -s /bin/bash - postgres
postgres(at)odin:~$ postgresql-dump -t db.out -dcivlp $PGDATA/../data.save
Stopping and restarting the postmaster
/var/lib/postgres/dumpall/7.3/postmaster -D /var/lib/postgres/data -p
5431 -o -d0
/var/lib/postgres/dumpall/7.3/postmaster: error while loading shared
libraries: libcom_err.so.1: cannot open shared object file: No such file
or directory
Failed to start the postmaster
postgres(at)odin:~$

Is any one able to point me the right way from here?
Thanks
Glenn