I get the exact same error as CouchPatato. I'm using Windows 7 64-bit with OneSwarm 0.7.5.0
I looked up the domain name registration information (did a "whois" lookup) for OneSwarm's website, oneswarm.org, and it was registered anonymously through a proxy registrant (a business that masks users so that you can't see their info in whois lookups), meaning, we don't know who owns OneSwarm's website.
oneswarm.org registration: http://www.whois.net/whois/oneswarm.org
I then went a step further by looking up the domain registration information for the site that registers domains. They registered themselves through GoDaddy.com. In fact, if you visit their website, you'll notice at the bottom that GoDaddy owns DomainsByProxy.
domainsbyproxy.com registration: http://www.whois.net/whois/domainsbyproxy.com
GoDaddy was recently found to support the retarded Internet Blacklist bill, so knowing that GoDaddy owns this masking service makes we wonder about the intelligence and honesty of the OneSwarm developers. Are they actively agreeing with the blacklist bill that allows Big Media to use ill-gotten legal powers to threaten websites out of existence?
OneSwarm, if you have any decency, stop using GoDaddy. Their servers run Windows (yet another political travesty); the company supports bogus bills in the USA; and their name sounds stupid.