no wifi after upgrade to os4.0.1

[HAL1275]

I upgradeed my iphone 3g to os4.0.1 after all attemps to regain wifi on 3.1.3 jb w/ redsn0w had failed. the phone has been jb w/ jailbreakme.com, but even before the new jb, i still had no wifi. it detects wifi, just says "unable to join xxxx", or occasionally "incorrect password". i've triple checked the passwords at home and at work; i'm using the correct passwords. my search-fu is alittle weak as i was unable to find any posts with similar issues. any help would be appreciated.

by the way; yes i tried to reset network settings as well. pretty sure this is relevent; the network settings don't show anything in the fields: they're all blank.