I was unable to duplicate the problem using the information learned by the traces you provided. I see that your first test site is also running Beta 2 and is not encountering the issue, which leads me to believe there is a configuration mishap afoot.
I have added another service to your members area. Please fill it out and I'll have a look. Unfortunately I've exhausted everything we can try without starting to significantly modify VaultWiki's files to see where the problem originates.