STRUCTAURAL  Works great for me. Running 1.72, worked well under my 30 mins demo (though had to restart it a few times to iron out router problems).

If your router (mine is a Sagem - used with Wanadoo/Orange) doesn't support uPnp (like mine), then the port opening detailed above (I'll resupply as one of the above posts is incorrect) worked for me and stopped the Protocol error). Helpful also it to make sure the PS3 is running when you start up medialink:

open ports:

TCP: 9386

UDP: 9385

I think it would be good for the developer to readme.txt this information, or stick it on their website.  
(Version 1.72)