I would guess this is a browser cookie issue and you can diagnose this by using another browser like Safari, Chrome, or Firefox. Install one of those from their perspective sites and try it. If the site works fine, it means that your browser with the problem needs to have it's cookies cleared. This is a common problem with folks who are not in IT and don't know that cookies are installed when you visit sites and they expire or go bad after awhile. So, if you clear them out then a new cookie is downloaded from the site and you're all well again. Lookup how to clear your browser cache in your browser preferences. I had no problems but I frequently clean out my browser cache.
