Don't worry, it's a normal error. DonationCoder uses a self-signed certificate for the site, and thus any browser will throw an error, since the certificate provider is not stored in the browser list of trusted providers. Just add an exception for it in Chrome and everything should be fine.
I think Gothi[c] (DC server admin) explained the site use of the certificate *somewhere* in the forum, but I can't find the post.