Loosing idle Putty sessions

I've never had problems with loosing ssh sessions with Putty until I installed a new version of Putty. I don't know if there has been a change in recent versions that affect keep alive. The solutions to the problem is to enable application level keepalive packets (not to be confused with TCP level SO_KEEPALIVE). To enable it enter a value in this field (I used 300 sec = 5 min):