Synaptic error

[Willis]

I tried to run synaptic today and received;

E: dpkg was interrupted, you must manually run 'dpkg --configure -a' to 
correct the problem.

E: _cache->open() failed, please report.


I brought up the Terminal and entered the command both with and without 
sudo and received;

bill at bill-spare:~$ dpkg -configure -a

dpkg: unknown option -o

Type dpkg --help for help about installing and deinstalling packages [*];

Use `dselect' or `aptitude' for user-friendly package management;

Type dpkg -Dhelp for a list of dpkg debug flag values;

Type dpkg --force-help for a list of forcing options;

Type dpkg-deb --help for help about manipulating *.deb files;

Type dpkg --license for copyright license and lack of warranty (GNU GPL) 
[*].

Options marked [*] produce a lot of output - pipe it through `less' or 
`more' !

With or without the sudo it returns the same result.  As a newbie, I'm lost.