Since I posted my previous Leopard question I thought I would try one more.

My wife and I own Macbooks. My brother and parents have iMacs. We all run Leopard. (all upgraded from Tiger)

We do like to use iChat to video conference. The problem occurs only with my parents' computer.

Their computer is one of the newer iMacs. they have the wireless keyboard and mouse.

Often (seemingly randomly) when we try to initiate a video chat, they get an error that they cannot start the video because the camera is in use. The camera is not being used, and I think it must be some error. Could it be due to the USB attached external drive (Maxtor) or the USB attached Brother Printer, or the USB card reader?

They took the computer to the Apple store and Apple just reinstalled the OS. But it still happens. I try to use screen share from here to check what is happening, but it is suboptimal.

I know sometimes there is a bandwidth issue (as my father has a computer setup from the hospital which uses enormous bandwidth to transmit images) but that's not always it as this occurs even when that computer (in the basement) is turned off.

Sometimes, this whole issue freezes the computer or it takes forever to be able to switch windows (you just see the pinwheel). Sometimes there is even a delay in ichat before my parents can see that I am logged in.

Any insight?

fuzz

Here is what I would do.

1) Check System Profiler and make sure the iSight is listed there.

2) Make a backup then try deleting preferences:
com.apple.iChat.plist
com.apple.iChatAgent.plist
3) Restart computer

If that doesn't work, use Disk Utility to repair permissions.

If that doesn't work, then try to create a new account and try iChat again. This usually fixes it because there is sometimes a startup item from 3rd party software which conflicts with it.

If that doesn't work, try resetting the SMC or PMU.

I have that trouble too, though I know that it only happens when I have my MacBook Pro hooked up to an external monitor with my laptop closed (obviously the camera would not work so well with the screen not opened). I am trying to think though as why such a message would appear on an iMac.

This generally happens when another application is using the camera--usually Photobooth. That is, Photobooth and iChat cannot both be opened at the same time--if they are, the second application to be opened will not have use of the camera.