Stuck on port forwarding

Every attempt on making the webserver reachable from the outside world (the world outside our internal network) using port forwarding in the pfSense simply failed so far. There was a moment it actually worked for a couple of seconds, when bridged interface on a cabled connection was used, but then we switched to wireless and it crashed again.

For the setting up part we used the information found on Group 1 (Group V.O.J.E.V.) 's blog. Here's a link to the certain entry:
http://vojev.wordpress.com/2011/02/28/enable-port-forwarding-virtualbox/

This is the simple rule that was added to enable the connection to the webserver through our router (pfSense):

How to forward ports and add rules see here: http://doc.pfsense.org/index.php/How_can_I_forward_ports_
with_pfSense%3F

There were help attempts from people who already managed to do this but unfortunately they failed too. Is it the system unstable, I don't know, but were working on fixing this nasty issue with all we've got and looking for other help if possible.