Last week this post on Reddit showed that Microsoft Reputation Service considers donate.fsf.org as a gambling site. This may look like a human error, maybe even someone outside of Microsoft, who knows, indeed, anyone can provide feedback to Microsoft and help them categorise the Interweb.
This means that you too can visit that page and help Microsoft's filtering system understand the difference between a gambling site and an FSF donation page.
Note, this is a Microsoft website it may behave strangely. Indeed I was not able to submit the form at first using Iceweasel or Chromium on Debian/Wheezy, of course I enabled JS. I had issues like the captcha not showing up, unwritable captcha field or the submit button not reacting. I left the page open for a while and when I got back I was finally able to submit the form (still, their captcha is harder to read than their EULA).
I tested the page using Tor Browser which gave me this user agent
Mozilla/5.0 (Windows NT 6.1; rv:10.0) Gecko/20100101 Firefox/10.0
and the page worked perfectly fine. I retested a couple of times and can confirm the same behavior. I can't say that Microsoft is intentionally being a dick with GNU/Linux users, but I can say if it's not intentional then their website sucks.