Remember your Buddies name because I am going to walk you through resetting iChat.
Quit ichat and go to /YourHardDrive/Users/YourUserName/Library/Preferences/ and delete the files com.apple.iChat.AIM.plist, com.apple.iChat.plist, com.apple.iChat.SubNet.plist & com.apple.iChatAgent.plist.
Then launch iChat again and re-set it up. This hopefully will reset iChat. Good Luck.