This is a known issue with Google Chrome and the AJAX Chat feature. I'm sorry but a fix is not going to be applied to it because the chat rooms are pending replacement by a different (3rd party) programme to help improve server speeds and efficiency.
If the AJAX Chat is the modification you truly want on your board you could upgrade to Advanced Hosting
, reinstall the AJAX Chat MOD and then apply the fix to it.
If you have any more questions please don't hesitate to ask and we'll be happy to help