Currently Being ModeratedNov 11, 2012 1:34 PM (in response to sakura_blossom221)
This can come down to the ports iChat uses to do the various features that may not be open in your MAc Firewall or your router.
For AIM in iChat 6 (Lion) the app logs in on port 443 to a server called api.oscar.aol.com (See the App menu > Preferences > Accounts > Server settings)
When it sends Files or Pcs in Chats then it uses port 5190 on the UDP Protocol.
Check System Preferences > Security and Privacy > Firewall.
Is the Firewall ON ?
If so Unlock the pane and use the Advanced Button.
In here does it Allow Signed Software to be allowed (Ticked/Enabled) ?
Is the Stealth option Unticked ?
Is iChat and IMAgent in the List of allowed Apps ?
Do you know what method your router is using to open ports ?
By default it will have ports up to 1024 open (allows Web Browsing and Mail apps that use ports that low)
As you can see the Login port is below this threshold but the File transfers are not.
IF your device has it use UPnP.
This allows the apps to "tell" the router which ports to open and they will close after periods of none use.
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
iMac 2.5Ghz 5i 2011 (Mountain Lion 10.8.2)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad
"Limit the Logs to the Bits above Binary Images." No, Seriously