I was having trouble getting Playon to work with my Xbox 360 when I recently switched from McAfee to Avast. (McAfee made my computer run uber-slow ...)

If you're having trouble getting it to run do the following:
Go to Web Shield -> click Customize -> Go to Basic tab -> In the field next to "Ignored Addresses", enter 54478

I'm not sure why this was the correct IP port but it worked and I had no issues playing hulu this evening. I stumbled across that port number and it worked when I put it in that field.

Excuse any technical inaccuracies in this post -- I'm just sharing what worked for me.

~RG