I'm getting that, too.
On the "unread posts since your last visit" page, I'm getting "Deprecated: preg_replace(): The /e modifier is deprecated, use preg_replace_callback instead in /home1/howsyou1/public_html/minmaxboards/Sources/Load.php(207) : runtime-created function on line 3" at the top and the text size of the thread links is something like 50% larger than normal. In threads, the quick edit button doesn't seem to work, too.
At a quick guess, either the website's PHP version got updated to version 7, which removed some of the backwards compatibility (specifically,
the /e modifier in preg_replace()). Thankfully, the error messages not only indicate what and where the problem is, but also how to fix it. It's probably all of a 2 minute job once someone with access can get to it (although depending exactly on how it was used, it might be more complicated).