I have seen certain browsers flag sites as dangerous because of the links in the spam posts. If this happens your browser wont allow you to log onto this site..
I do run firefox and adblock plus. If there are certain links in the spam threads firefox will flag the site as dangerous and not allow you to log on.Download a newer browser like FireFox or Google Chrome. Both are much easier and faster to use than Internet Explorer. Then download an app/extension called "Ad Block Plus" and you will never see another advertisement again. This will also prevent your browser from blocking you access, and will make your web-surfing safer as a whole.
Sounds like the administrator on that site doesn't really know how to make the changes necessary.Be careful what you wish for, another site I am on recently updated to the latest and greatest...What a pita, I get some sort of sql error that they can't fix after a few minutes of being logged in with my original screen name from 07, to the point that I can't even vew the forum as a guest in IE, I have to use Chrome and a recently created sockpuppet account. And they are harder on newbs than Pirate.