check the logs in /var/log...especially /var/log/messages. To quickly check this file for mentions about gaim, try
# grep gaim /var/log/messages
I dont use gaim or yahoo messenger, so I don't know for sure if they put a log file in there. If not, you can always try, as root, the following two commands...
#locate gaim |more
and see if any of the files it locates look like log files.
Sorry I can't give you more to go on, but /var/log is typically where the log files are located...