Sites that Have Trouble with the Content Filter / Proxy Server
Some sites fail to work properly through the content filter or through the web proxy. There are a number of reasons why this can occur but most typical are:
Site uses authentication method that requires non-proxied connection
Site uses proprietary protocols, wrappers, or methods which the content filter or proxy interprets as garbage
Site uses proprietary protocols, wrappers, or methods which the content filter or proxy interprets as a virus or malware
Site uses malware, spyware, or other known tracking vectors which is correctly classified as such and you have those options enabled
Site violates HTML
Site has browser specific requirements which cannot be proxied well
Overcoming broken sites
The primary reaction would be to white list the main site but often the error comes from an element of the site which fails to register in the URL bar. You can find out what that element is and whitelist it or add it to the web proxy bypass by following this guide. Using this process, you can discover the particular elements that are getting jammed and add their domain names (NOT THE URL) to the web proxy bypass. Please also join the discussion on the community site and add any sites that you find.
Common bad actors
The following are some sites which are reported as being 'bad actors' with the content filter or web proxy. Some administrators add similar lists to either their 'Web Proxy Bypass' and/or to their WPAD configuration file and firewall exemption lists.
Oracle - Sun - Java