Try this after download the latest package of ncurses:
ls -al /var/log/packages/* | grep ncurses*
If it lists ncurses first remove the package like this:
removepkg /var/log/packages/ncurses*
This will remove the package and now if you grabbed the tgz from the ftp site I mentioned above, simply do this, after moving the package to /var/log/packages
installpkg ncurses.x.x-i486-0 (note you will want to put in the actual version numbers you downloaded, etc)
This should fix the problem the majority of the time. If that doesn't work, let us know as a whole reinstall is always the last option when dealing with Linux.