No sound when video chatting - 'microphone enabled' grayed-out during chat

Question

Recently, whenever I video chat there is no sound on the other end. 'Microphone enabled' is grayed out. It is not grayed-out when I am not video chatting. All sound preferences appear to be set correctly. This problem just appeared recently.
Thanks in advance for any suggestions.
Bob

Answer 1

Hi
Would tend to work towards deleting that file as part of a process.
The original reply was quite long in the first place and trying to incorporate more "If that does not work... " statements I felt would only make it more confusing.
com.apple.ichat.plist
This holds all the info in the iChat Preferences except the Accounts pane stuff.
It also holds the results of a hardware check at each iChat Launch which includes checking the Internet Speed available and re-writing the .plist accordingly.
The Hardware Check also reads some info from the System Profiler info (at least the same places System Profiler gathers it's info).
This means if the System Profiler would not be able to "See" a Mic or a camera then any App cannot either.
Some of this info is held in the PRAM memory as are some volume settings and resetting the PRAM may have helped.
The reason I hold off suggesting the Deletion of the .plist is that it does hold so much info especially if you have changed the settings:-
Any Changes to the Font, it's colour, the background of the IM colour in Messages.
As Messages also show you any Background Pic you have for Text chats that gets deleted even though set in a Menu item
The Overrides of incoming IMs
Save Transcripts and and sub items
Which Mic is selected in the Drop down in the Video Section. Same for Output choices if you have them (and cameras if you have two attached).
The Menu Bar icon and it's sub items in the General section.
Changing to Available at iChat Launch.
In the alerts section anything you have set to a Different sound or to have an Apple Script activated.
As the above can be set individually in the Buddy list (Highlight a Buddy and then do a Get Info (CMD+I keys) and Alert tab) you also lose those settings.
Several menu choices such as Enabling Screen Sharing (Video Menu) and the Show items in the View Menu, plus the Message style (Sub menu item in the View Menu).
These are what I consider to be the more important changes/losses deleting the .plist involves as I have changes in most of them.
Obviously not everyone does the same and the effect for you may be less involved.
It is hard to pinpoint the .plist itself as the item that is corrupt as it reads so many things from other sources.
It is possible that it is not getting written to after an update for some reason.
Upgrading from Leopard to Snow Leopard can leave some iChat 4 info in there. Mostly these are just floating bits of info at this point, but can contain the path to reading something that got moved in the OS Upgrade.
At the end of the day, like any other bit of info on your computer, it can get given erroneous info. This is most like to occur if iChat is subject to a Force Quit or suffers an Unexpected Quit or a particular chat fails dramatically.
There have been no updates to iChat since OS 10.6.3 when it got updated to iChat version 5.0.3 so I don't see it as an "update" issue.
Summary.
It can be anything that causes it.
Of any changes to the OS then an Upgrade may be more likely.
Deleting the .plist is best reserved as a last resort as it holds so much info about settings you may have changed.
I have given you a list of many of the things that get changed.
It is most likely caused by some other info that the .plist has read into it by the iChat Launch.
Hope this explains things a bit further.
That's not to say that sometimes someone may post with enough info and clues to what they have done so far to suggest deleting it straight off.
8:41 PM Saturday; January 15, 2011
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"