I've hosed my own system several times over. Sometimes it's not your fault, but you should pick the best tools for managing your packages (I'm surprised no one mentioned "aptitude" yet! You get to examine package conflicts and decide to accept/reject certain actions.)

a brief tale of shared blame:

I surf through my packages and see a newer version of libc6. Huh, okay--let's install it. No new packages listed (I should have checked the "removed packages"). Go!

Then, I realize in horror that almost everything on my system has been uninstalled. Turns out all the dependency information did not carry over to the new libc package. It cost me a few hours to dig through the cache, generate a list of packages and run "apt-get" on the list.

Chuck

On Sat, Dec 21, 2013 at 4:23 PM, Will Godfrey <willgodfrey@musically.me.uk> wrote:

did the debian devs think they were doing?

My music machine is set up precisely as I want it with no spare fluff or
eye-candy, and fits my workflow like a glove. I seldom make any changes, but
thought it high time I checked for upgraded packages. Up till now this has
never been any kind of problem and usually results in some tiny overall
improvements.

Today was different. Without asking, indeed, without even a warning, they
installed GDM, Gnome3 and pulse audio, thus rendering my computer totally
useless. The only thing I could do was reboot, then log into recovery mode,
find aptitude and delete the crap.

I will never really trust debian again :(