problem with dselect/dpkg

[Helen Cook <helenco@interchange.ubc.ca>]

When I run dselect, and try to install packages this is what happens:
packages are downloaded correctly, it has trouble removing adbbs (but i
think this is unrelated to my main later problem), it gives me the 'Some
errors occured while unpacking...' message, i press enter to continue, and
it spits back: 

/usr/lib/dpkg//methods/apt/install: /usr/bin/dpkg/: Not a directory

installation script returned error exit status 100.

and my remaining packages that need configuring, aren't.  If I run dpkg
--pending --configure manually, it seems that nothing actually is
configured, either. 

TIA for any help,

Helen