So, recently I updated my iPhone to 3.1.2. Unfortunately, the custom firmware image I used contained both Cydia and Icy. I don't own an Apple computer myself, so I am unable to build my own custom IPSW, so I asked somebody else. And no, I will not use redsn0w because it sucks. It never worked for me on my iPhone 2G, it always came in recovery mode while it should go in DFU mode. Or was it the other way around

Now it seems, if you install both Icy and Cydia, that Icy messes up the Apt/DPKG database. Joy ... Cydia errors when trying to install anything:

Cydia: Error Couldn’t configure pre-depend dpkg for ncurses, probably a dependency cycle.

Makes me wonder which smartass got the brilliant idea to write yet another package manager for the iPhone. Installer was fail, Cydia fixed that. Why did we need Icy again? IMVHO, people should stop reinventing the wheel... So, if you didn't update to 3.1.2 yet, make sure you choose either Cydia OR Icy. If you choose both, you have to restore your phone to solve the problem. And this problem occurs with both redsn0w as with installing from a custom IPSW built with Pwnagetool.