The "apt-get fix command" you're remembering is "apt-get -f install" which actually tries to repair failed installs and correct the dependency issues apt-get did not manage to get right. Also, if a package is giving you a hard time, and has become half-installed thus placing your system squarely into dependency hell; try removing the package. Generally apt-get remove XXXXXX works even if the package is only half installed.

I have to echo the concerns expressed by rickenbacherus above. Simply changing a whole bunch of your sources and the apt-getting upgrades in a manner I can only think to describe as "Willy-Nilly" is just plain stupid. Worse, it's incompetent on any debian release which is not sourced purely from stable. If you have to have some new package, download the tar or tgz file, follow the installation instructions and keep yourself from going mad. If you need some packages, the documentation is sure to tell you. With any luck, you'll get through with as little a learning curve as needed. Also, again along rickenbacherus lines, learn apt-get, because it is superior to my last suggestion, but used incorrectly will make your linux machine more of a nightmare than M$ machines. Except for the crashing, of course.
Hopefully.

Good Luck,

Civ