In using the HttpAPI to automatically login users from my main PHP site into the Web Wiz Forum, I encountered a bug in HttpAPI.asp file that was returning an XML error.
The script is correctly encoding the Username's with Server.HTMLEncode(), however it isn't doing the same for the "User_code", which can also contain non XML friendly characters.
I have modified this one function to:
vbCrLf & " <CookieData>" & Server.HTMLEncode(rsCommon("User_code")) & "</CookieData>" & _
Posting this to help others, and so this can be fixed in future releases.