Problems after upgrade: Leopard to Leopard no longer works

Question

My sister upgraded to Leopard on her iMac(c2d) to Leopard yesterday. Earlier in the day we were able to do video chats with a number of people(her machine Tiger to Fathers machine Leopard). However, since upgrading, we've experienced weird behavior for video chats. Basically in her window she won't see her image(the small one), and I don't see her at all. We've tested this out with a number of other iChat accounts and get the same results. Btw, all machines that are chatting with her are using Leopard. Also, all other forms/capabilities work: screen sharing, sharing of pictures, audio chats.
Anyone out there have similar problems after upgrading from Tiger to Leopard? I have done the usual adjustments of bandwidth and QT settings, as well as restarts. What else should I try?
tia,
n

Answer 1

I finally resolved this problem: I think the issues/steps would be helpful for anyone who experiences iSight off or not working problems after upgrading to Leopard(then to 10.5.1) on a intel 20" iMac :
Problem:
-If you have an internal iSight on an iMac and your camera works fine in Tiger
-If you upgrade to Leopard
-If Chat camera doesn't show your image (iSight off) even though the green light is on
-You can see the other persons video on iChat
-Your friends can here you and you can share screens, files, etc.....everything but have them see you
These are the initial steps I took:
- Deleted the pLists(or stored preferences for the Application) described at the top of this thread
- Was told it might be slow internet connection so did various things: disconnected other computers, changed wireless to "G" only
- Specifically Opened of ports spec'd for Leopard on router (even though I hadn't needed to do this under Tiger)
- Tried chats with various people on various fast/slow networks
- Restarted all aspects of the network: router, wireless access point, computer
- Checked to see if the iSight was shown in 'System Profiler'. It was found in 'About This Mac->More Info->System Profiler->USB'
- Clicked Video icon in iChat Buddies window(to the right of your name) and coudn't see my image
- Opened 'PhotoBooth' and coudn't see my image(black screen)
- Opened iMovie and couldn't capture video via the iSight(black screen)
- Opened iChat->Preferences->Video and couldn't see my image
- Validated that 'Camera is Enabled' in iChat->Video->Camera is Enabled
If you are experiencing a similar problem with you built-in iSight, I would probably focus on the last 5 things that I did. What they showed me was that the iSight was just not capturing video even though it was capturing sound in 3 different applications.
The solution to iSight Off or iSight Not Responding or No Video is......reset your computer! I had thought my sister performed this but it turns out she hadn't. Here's the link to this procedure:
http://docs.info.apple.com/article.html?artnum=303446
Very easy to do though: Power off computer and unplug all cables, including power cable for at least 15 seconds. Plug everything back in and power up the computer and retry clicking on the 'Video' icon next to your login name. If you see yourself then...problem is solved.
While I eventually found posts in several other forums, it took me the better part of a week. To try this simple step. I wish I had done so straight away. Oy. I guess I learned a lot about ports, speed etc.
I hope this helps.