MrQ, I didn't think anyone will use more than 1 channel because IMO it's the best to put all users in 1 channel so they can chat one with the other.
About the other thing, I dunno why does it happen. A workaround can be to add the ubb_whos_online.cgi that was removed in the upgrade (put it after $ct = $ci + $minutes;), and then remove the 'require "ubb_chat.cgi"' line from ubb_forum_summary.cgi.
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