The Kunena team has announce the arrival of Kunena 7.0.4 [K 7.0.4] in stable which is now available for download as a native Joomla extension for J! 5.4.x/6.0.x. This version addresses most of the issues that were discovered in K 6.2 / K 6.3 / K 6.4 and issues discovered during the last development stages of K 7.0
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Using 1.6.3 on Joomla 1.5.22. Approximately three days ago my users report that posting new topics or replies result in a "Your request timed out. Please retry the request." if they take more than 60 seconds to input the message before "submit".
This does not seem to occur with Firefox 4.0 but does with Chrome 10.0.648.204, IE9 9.0.8112 and Safari 5.0.4.
I reset php max_input_time but it had no effect upon the problem.
Set your Joomla Session Lifetime to 30 minutes (i.e. equal to the same as the KunenaSession Lifetime = 1800 seconds) turn Session Handler = none and see if this makes a difference?
You might also try resetting all your Kunena configuration settings to their defaults (there's a Default button for this purpose on the Forum Configuration panel