Cydia crashed, iPhone unstable, need help!!!

[HAL1275]

Hi all. I have a JB iphone 3g on 3.1.3 jailbroke on redsn0w; can't recall software versions right now cause I'm at work. About a week ago, Cydia crashed in the middle of an update; now it dosen't recognize any of the packages that are installed, yet they still work. The real problem, however, is that the device has become unstable: whenever i try to respring it or power it down then back up, it gets stuck in a loop going from the boot screen to the lock screenand back. I can get the phone functioning by using redsn0w and selecting "already owned", but before the Cydia crash, my jailbreak was untethered. How can I fix this?

[jkmonkey]

Do a fresh restore to 4.0.1 and rejailbreak with redsn0w 0.9.5b-5

[HAL1275]

Can I then downgrade to 3.1.3, some of the packages that I like aren't working yet on 4.0 AFAIK

[jkmonkey]

oh ok. If you want 3.1.3 just download a 3.1.3 shift+click restore to that then jailbreak with spirit.