You're a Bunch of Factors

I havent tested on Vista as I don't have easy access (benny the cunt had an issue), but noticed when compiling, there is an option for Vista's UAC. I left this at default 'none' previosly, but have now set this to 'Highest Available' (choices are none, As Invoker, Highest Available and Require Administrator) so hopefully that should fix any Vista issues, but from your post benny the cunt it seems it IS clicking the 'Register' button, so not quite sure... Might be a timing issue also, but it was set to pause 3 seconds between actions, but I modified to 5 just to be sure....
I also thought it might be a screen resolution issue, I run at 1680x1050, and I tested it at 1024x768 and 1920x1050 (highest I can go) and it still worked fine for me. I hadn't really thought of screen resolution issues before, but it seems like they have no effect anyway.

So here is final version (unless any issues reported ). Exe now works fine, seems it was just a variable name conflict error in compiled version, bug has been reported to AHK support.
I have just registered and unregistered for a tournament 10 times, all successfully, so I can't see why it wouldnt work for others?

This zip contains a folder structure:

So you can run the exe, or if you choose, the script if you have AutoHotKey installed.

If there are any issues, such as some had in using this, please post them here as original thread is now locked.

i used this today and it worked. woot