Hi,
You say "normal login and Password".
Do you mean you have an AIM name that you used somewhere else before that did work ?
Do you mean MobileMe name and password that works elsewhere like Mail ?
iChat can use Screen Names that are registered with AIM or Apple email IDs from MobileMe that are recognised as valid AIM names (As well as older style @Mac.com names)
iChat can also use Jabber and GoogleTalk names (Google requires that you Enable Talk on your Google Account).
The ID you use to Login to Apple Discussions or iTunes may not be a valid iChat Screen Name.
9:19 PM Sunday; August 8, 2010
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"