I jailbroke my iphone 2g using pwnagetool and at first it went fine. I got to the springboard and everything was there, but when I tried to go into cydia it opened for a second and then went back to the springboard. I assumed that there had been a problem jailbreaking it so I tried to restore it with the custom firmware again. It gets stuck on "preparing iphone for restore" and then I got an error, so I tried using the 2.2.1 custom firmware. That didn't work either. I tried entering DFU mode and doing it and that didn't work either. Then I tried making a new 3.0 firmware using pwnagetool and that didn't work. The regular 3.0 firmware works so now I have an unjailbroken iphone that won't become jailbroken no matter how many ways or versions I try.

I got exactly the same problem the other nite! except my phone (2G) wont go into DFU mode anymore ....it simply doesnt turn off, just reboots itself when you try to turn it off.

Now you have a regular 3.0 firmware ? Just use redsn0w and unjail and unlock it, and you're done. (you must have a intel mac, or a pc with osx86)
This has worked for me.

David

It jailbroke it but cydia still isn't working right. But this has happened to me before. This time I'll just see if it fixes itself.

I just tried icy and it works fine! So I don't really need cydia. Thanks

Icy doesn't work. I didn't post this earlier because I just gave up. sorry.

What I did was, I installed cydia and Icy seperately. It actually told me what to do on the cydia homepage