Hi Kenneth,
1. I get the same problem with the default "Simple Upload with Progress" demo.
I also get the same problem with Internet Explorer, in fact even worse, because after the first click the button becomes disabled, you have to wait for it to become enabled again to do the second click which shows the upload screen.
2. I don't get the same problem at http://www.ajaxuploader.com/Demo/
So it must be something with my server installation.
3. Both example files give me the same errors: I have to press the button twice, and the JavaScript errors are present.