Ray,

I had the same issue at work when they made some big IT changes (that never do anything positive, only gum up the works). Not necessarily the same message, but this site was blockd due to some of their general keyword filtering.
After about 2-3 weeks of not being able to access the site from my work computer directly, or through bookmarks, one day I clicked on a thread link that was in one of my notification emails from the site. VIOLA!! It accessed the site without issues and allowed me to navigate around the site. After 2-3 weeks of accessing the site that way, I found that it must have become "recognized/accepted" and now I can access it via bookmark, typing in the url, etc.

If you get email notifications from the site, try that. May not work, but it worked for me.