BES is a Blackberry Enterprise Service and won't help you with this. You are getting this message because the browser you are using can not load the page you are trying to visit. If this is a page you really need to visit, I would recommend downloading the free OperaMini Browser. You can find it from your BB's browser here: www.operamini.com. This browser seems to work on a lot of the pages that the built-in browser can not open.
Good luck and Welcome to the Stacks.