I might be wrong, but having all those ports (1-50000?) might be screwing the router up as well as leaving you open for attack.
I run a LOT of multiplayer games online and I just use UPnP. Game installs should check the firewall. I am also running Steam games (including HL2) on Windows 7 64 bit.
Try removing all your port forward rules, swithc on UPnP on the router AND in windows (you need to go to control panel, add/remove programs, then click windows components, then tick the box for UPnp) then try running your games.
I would seriously NOT recommend leaving all those ports open the way you have done it.