gotta restore it with the official apple 3.1 fw. Once you're fully on 3.1 (unjailbroken) then create a custom fw with the pwnage tool. then restore from the custom fw and that's it. That worked for me.
Oh... Haha. That's what I'm already doing (when I get home I'm going to Pwn it, on Vanilla 3.1 now). I thought you said you edited a Plist and got it to fix.