Depending on what exactly
you were doing when you were trying to "go to the Addventure" it may have something to do with an apparent reconfiguration of the web server recently to disallow folder browsing by visitors to insecure websites.
Sometime a week or two ago, the web server stopped allowing URLs of the form http://www3.bearchive.com/~addventure/recents and instead requires the use of http://www3.bearchive.com/~addventure/recents/index.html
I'm not sure when that change went in, but it took me a couple days to figure otu what had happened and rewrite the links in the Addventure pages to link to the more-specific URLs.
It should be right now, but be sure to check any bookmarks you've made yourself to make sure they're using the new form -- otherwise, you could have the same problem as before.
There have been a number of security-related changes to BEA over the past few months. Personally, I welcome them, despite the occasional reorientation glitch like this.