and yeah, that's it. The "Search-Button" in the forum isn't respondinging at all, while all other links seem to function.
I also tried different browsers.
Site Specific Search:
Often, you want to search a specific website for content that matches a certain phrase. Even if the site doesn’t support a built-in search feature, you can use Google to search the site for your term. Simply use the "site:somesite.com" modifier.