I just used PwnageTool 2.0.1 to make the move to 2.0 (1st gen iPhone, T-Mobile, from 1.1.4 unlocked/activated). All went fine ... but whenever I try to start Cydia it simply closes down right away.

After some reading I noticed that restoring your old settings through iTunes is not such a good idea so I tried Reset All Settings. To no avail ...

After that I tried re-doing the entire PwnageTool,... even tried using expert mode ... but still Cydia will not do anything ...

Anyone experiencing this too? Anyone know a fix?
I'd love to have OpenSSH running (amongst others).

Im assuming your a mac user?

I did my 2.0 install on windows with a premade IPSW. I couldnt get the make-my-own to work either on a hackintosh computer. I would suggest trying one of the premade ones.

Also before I installed I made sure my BL/BB was Boot Neutered. Not sure if that makes a difference.

There are some things for you to try at any rate.

I am having the same problem too. This happened to all my apps when they would all crash back to springboard without starting. I uninstalled them through itunes and reinstalled them through App Store to fix the official programs like AIM and other App Store programs. Yet, I was wondering if there is a way through SSH or something to uninstall Cydia and reinstall it. Seems like that fixes the crash to springboard problem.

I neutered the BL/BB ... and yes I'm a Mac user.
I try to stay away from pre-made ones (note: I tried creating one with simple mode, didnt work, and one in expert mode adding some of the Cydia apps, didn't work either), since you never know who did what with them ...
I'm basically trying to SSH as well ...

Oh forgot to mention that the iTunes store apps work fine ...