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The sidebar widget will help the page rank, but it is at a disadvantage. Google's understanding of the sidebar makes the content in a sidebar less effective (my opinion, please do your due diligence). Most sidebars include links, content around advertisements, and generic information. This has resulted in the understanding that content in the sidebar should carry less weight for rankings. I suggest building up a strong intralinking website architecture. Build those landing pages with unique content, link back to the home page for your parent keyword phrases. Make the slideshow as HTML friendly as possible (can it be done completely in HTML/CSS?) and fill in your alt texts. Ideally, your home page would have content to help its rank. Can you show content through tabs, modals, or other interaction methods? This way the content is not a focus to the user, but does exist on page for those who want it.

More than likely it was one 3 things, a DNS issue, a peering issue, or a temp ban. If you were currently ftp'ing into the site and had too many threads open, usually above 4 or 5 but all depends on the server setting. They can issue a temporary ban on your ip address for the site. Depending on how the server is set up, you can either get an explicit message, which is bad. Or you can just get an error like you, which is good and it means the server is shedding the load. A DNS issue could be that a name server is down somewhere or having other problems. You generally cannot do anything about this and they are generally fixed quickly because of the amount of sites / information hosted on them is vital. A peering problem, like a DNS issue is usually spotty. More than likely that is what was happening. A peering issue means you cannot access the "chunk" of internet that the peer directs traffic through. So say you can access 99.9% of everything you want, because it is not going through the peer with the issues. The best tools you can use to diagnose these problems are TOR, it is a socks proxy that routes your traffic so essentially you will be accessing the site through another isp, who could not be having peering or DNS issues with the hosting isp. Also you can use http://www.whatsmydns.net/  which will let you know what different dns servers around the world are returning. It will let you know if a major DNS server is having an issue. For general checking you can use this as well, http://www.downforeveryoneorjustme.com/