apt problem

[Cheatah 0#@!^]

When i try to select "ADD or REMOVE........." from the k-menu in my
kubuntu 6.06 it shows an error message like this-
"The APT Database could not be opened! This may be caused by incorrect
APT configuration or some similar problem. Try running apt-setup and
apt-get update in terminal and see if it helps to resolve the
problem".
i also tried it in the terminal, the error message there is that it
cant find lib.....
what is the problem?? how can i solve it??