Recently, iChat fails to even open

Just recently, sometime after the last Quicktime update that occurred with Software Update, iChat started failing to launch. The black arrow occurs under the dock's icon for about a second and then disappears. I first tried restarting, but I got the same behavior. Then I logged in as a different user, got the same behavior.

Next was to check error logs, here is what I found:

dyld: Library not loaded: /System/Library/PrivateFrameworks/VideoConference.framework/Versions/A/VideoCon ference
Referenced from: /Applications/iChat.app/Contents/MacOS/iChat
Reason: image not found
Trace/BPT trap

Then, I reinstalled iChat from the Mac OSX install disc, assuming it would write over the old application. That didn't work. Then I trashed the application and reinstalled from the disc. The finder showed iChat version 3.1.5. I'm not sure if that's the latest version, but Software Update says no new software updates. It still didn't work.

I don't use instant messaging too much, but I had been trying to use iChat recently for a video chat. I do have Adium installed and it works fine, but there's no video.

Does anybody out there have any good ideas that might help me out?