Ichat User Unable to Receive Messages

A co-worker was having a very strange problem in that they were not able to communicate with anyone via Ichat.  They were able to send messages, but they could not receive responses and they also could not see their own messages that they were sending.  However, screen sharing and voice chat was working for them.  After confirming that the problem was isolated to the user account on the MAC (this was done by signing in as a different user profile on the Mac Book Pro), then connecting to Ichat from that new profile to verify if it was still working on the machine itself.  Once it was confirmed that Ichat was not the problem, we decided that there must be something wrong with the user preferences.

Logging back in as the affected user, we opened the following location and deleted all com.apple.Ichat.*.plist files:

/Users/USERNAME/Library/Preferences/

Upon deleting those files, once Ichat was relaunched, we were stepped through the setup process as if we had not used Ichat before. Once the user filled in their information, everything started working just as it should once they connected.  Very strange little problem.