I changed your password (just emailed it to you) in an effort to duplicate the issue. I'm currently looking into it and will keep you posted accordingly. In the mean time, is there a download link or anything that we can assist you with?
Unfortunately it doesn't look like there is anyway for us to resolve the looping login issue on our end, and the only workaround is to create a new profile with a different email address. Our apologies for the inconvenience.
I'm also trying to download Autodesk Inventor Professional 64-bit and I cannot download any version from the site, regardless of the way I choose (browser download, install now etc.). I tried to do it on 2 different OS (Windows 7 and Linux) with several web browsers, and it always looks the same: I get to download page and when I click "Install now" (or "browser download" or anything else) nothing happens. I waited for a long time for the page to download. I would be thankful for sending me download link via e-mail.
I just confirmed that all Inventor download methods are functioning properly and am not sure what was causing the issue was on your end. With that being said I've just sent you timed direct download links via Private Message. I also wanted to point out that for future reference, the majority of our current version software can be downloaded form our trials page as well.
Please let me know if we can be of additional assistance.