problem with apt-get upgrade

[Margaret Toews]

Last week I did an apt-get upgrade on my 2.2.17 OS release which error-ed out with "E: Sub-process /usr/bin/dpkg exited unexpectedly". Since then Apache and Samba are broken, and I can't uninstall or re-install anything using apt-get without getting the same error.  I re-installed Apache fresh and can probably do the same for Samba, but I'm wondering what happened, if anyone else has had this experience, and what to do differently.   Thanks for any help.   Margaret