If you notice, it's not the "site" it's isolated to the forums only. As explained many of times in "website suggestions & problems" it's an issue where by the forum code is pulling a huge amount of DB queries, causing a bottle neck within mysql. When there are more people browsing the forums, it becomes slow and 404 errors occur. As a temporary solution, you can just hit your refresh button and the forum should load. There are 2 ways I can go about this; 1) Install new forum software, this means no integration with the website, you will have to sign in twice, no posts will be transferred