Frozen pagination buttons and 'mark all as read' link

Steps to reproduce:
1. Go to http://javatalks.ru/topics/recent
2. Go to any topic
3. Press browser's back button

AR: pagination buttons and 'mark all as read' link are disabled and can't be pressed for about 30 seconds, but afterwards it become enabled

ER: pagination buttons and 'mark all as read' line are able to press at once after return to the recent activity page

Note: reproduced only on the production javatalks.ru, on the qa.jtalks.org/jcommune it can't be reproduced