Cydia fails to launch on iPT2 4.2.1

[FuRrY321]

Using iOS 4.2.1. I am new to jailbreaking, so I don't know if this is intentional or not, but when I try to launch Cydia from my greenpois0n-broken iPT2, it immediately goes to a white screen, then goes to the lockscreen. I realize you can access the Cydia store from Safari, however, I was hoping to add my own custom source.
Thanks for any help in advance!

[lanulos]

try rebooting?

[FuRrY321]

I am sorry if I appear annoyed, I know you're just trying to help, but common sense would dictate that that's the first thing you should try. So yes, I have rebooted. I think, since I haven't yet synced any media to the device since Jailbreaking, I will try restoring then re-jailbreaking using redsn0w, as I have read quite a few success stories regarding that but not as many with greenpois0n.

EDIT: Nevermind, I have successfully restored/rejailbroken my iPod with Greenpois0n, there was no need to use redsn0w.