Hi Jim,
I'm sorry you had no answer, we want to make sure community is aware of Thwack more in future. Regarding your issue:
More details would help to identify the issue. Is there any proxy between client and server? Do you have server logs and if yes is there something what would give us a hint? Is this problem only with this server or do you see it happen with other too? What about other client side machines, do you have the same problem from other systems?
Peter