On one of our 11.5.10.2 instance, users started receiving the message "The webpage you are viewing is trying to close the window. Do you want to close this window?" whenever the user session is timeout. Once the user relogin, it will again taking him back to login screen. The user has to close all his work and relogin everytime.
Solution : This is the settings issue in the Java Plug-in. Goto
Control Panel -> Java -> Advanced -> Java Plug-in -> Uncheck "Enable the next-generation Java Plug-in". And restart the browser
