Try going to Menu/Settings/System/Repair and Formatting Tools/Clear Temporary system files and cache
You will then have to enter your network key again (If Wireless) and see if that solves the problem. I had that problem too at first.
I also disabled my firewall completely, or at least I thought I had, I was running Norton Internet Security. The TV+ still would not work, so I uninstalled Norton (Extreme I know
) then it worked. So after I installed a different firewall and it is perfect now. I should add that even when it was not working I could (as you say) see it within the media sahring box on WMP11.
Give both a go try the cache remedy first,