I have exactly the same problem and symptoms with my Ziova and have tried everything you have + an MTU reg change to no avail.
I had this working in Vista 64 until this evening when I put windows 7 on. In Vista 64 (and prior to that XP) I also had to do the guest account, permissions, change local sec policy etc but it worked. Despite doing all this 7 really doesn't want to play. I really don't want to go back to Vista but if I can't sort this I will have to consider it.
If I figure it out I will let you know, if you do before me please post the solution.
Good Luck
