You should probably just delete the old keychain from iChat, because it might be corrupted. So the next time around, when it asks you from a password, it might remember it.
Finder, Apps folder, Utilities, Keychain Access, select the iChat Keychain and press delete.
Shop for your Apple, Mac, iPhone and other computer products on Amazon.
We are a participant in the Amazon Services LLC Associates Program, an affiliate program designed to provide a means for us to earn fees by linking to Amazon and affiliated sites.