Hey James,
Thanks for looking into this.
The main one is found here
http://www.wlac.com/listen.html. It is a radio station's live stream. I have found the problem elsewhere when i tested in places like ifilm.com.
We have a proxy, but the way Wingate is setup, it seems to be optional whether or not you want to use it. We mainly employ NAT.
Our only plugins are your Puresight content filter.
I can say with certainty, that this problem consistently started after upgrading Wingate.
Thanks for your help.
Matt