I was trying to use the ColdFusion 8 Ajax debugger and could not get it to pop up, despite having that option enabled and my IP address (127.0.0.1) in the debug IP address list. Eventually I discovered (by mistake) that if I used “127.0.0.1” in the URL then debugging worked, but if I used “localhost” it did not. The problem? IPv6 (used by default in Vista), where localhost maps to “0:0:0:0:0:0:0:1” instead of “127.0.0.1”, causing the IP address to not match what was in the allowed debug IP address list. The solution is to simply add “0:0:0:0:0:0:0:1” to the list of allowed IP addresses (or just access CF Admin using “localhost” and click “Add Current” which will add that address). We’ll fix this by the time we ship CF8 so that 0:0:0:0:0:0:0:1 is also a default, but if you are using the ColdFusion 8 public beta you’ll want to add this manually for now.