apt-get upgrade

["Johnno" <valentine@xtra.co.nz>]

Hello

When I do a apt-get upgrade on one the the servers here I get this error
message:

Do you want to continue? [Y/n]
dpkg: `ldconfig' not found on PATH.
dpkg: `start-stop-daemon' not found on PATH.
dpkg: `install-info' not found on PATH.
dpkg: `update-rc.d' not found on PATH.
dpkg: 4 expected program(s) not found on PATH.
NB: root's PATH should usually contain /usr/local/sbin, /usr/sbin and /sbin.
E: Sub-process /usr/bin/dpkg returned an error code (2)

dpkg package is install, any ideas?

Many Thanks,
                   Johnno