Firstly, what's your website address? I know of a site that's using Canaca as their webhost but the website is up at the moment. Therefore, I think the issue will either be with the DNS or your system.
When the problem happens again, go to www.dnsstuff.com/ and run a traceroute on your domain and reply back with the results. Right now your site is comming up for me so it's hard to debug a problem that is not re-producable.
