Network Discovery

Ok, so i built my computer in June 2012, pretty beast system. However, I recently installed Emit, wich is basically a uPNP/DLNA add-on which streames content to various devices with on-the-fly encoding and loads of other good features. Once I let it through a firewall, it started playing up. Now I cannot see other computers on the network, and other computers can't see it. I've tried programmes like Malwarebytes and CCleaner, but they just don't seem to cut the mustard. For example, I have a picture of the exact problem:

 

<a href="http://imgur.com/Z2KszHd"><img src="http://i.imgur.com/Z2KszHd.jpg" title="Hosted by imgur.com" alt="" /></a>

Despite there being 3 other computers on the network at once, none show up. (http://imgur.com/Z2KszHd)

 

<a href="http://imgur.com/VaYbjiV"><img src="http://i.imgur.com/VaYbjiV.png?1" alt="" title="Hosted by imgur.com" /></a>

My phone cannot discover My Computer no more :( (http://imgur.com/VaYbjiV)

 

Also, at LAN parties, no devices are discoverable, which kinda sucks. 

I think the problem resides in the firewall. However, turning the firewal off doesn't seem to do much (or anything) to make my situation better. I have even tried a system restore to a previous point, which was a complete waste of time. So, what should I do? My next option is pay the computer guy in our local village £20 to take a look. And that'll be another £50 for him to get up off his arse and do something about this problem. 

 

Thanks, Tom