We checked all plugins we used for the themes, and found the problem. It is the “Smooth scroll” plugin that seems to be not compatible with the most recent Chrome release. We talked to the jQuery plugin developer and he told us that there was already a problem with a Chrome release, but de facto it was a problem with the Chrome release, not with the plugin. Some days after Chrome fixed it with another release. Looks like this time it is the same event.
To remove the plugin, you can open the file “plugins.js” in the folder “script and remove the plugin by deleting line 7 – 26 (starting with “/* SCROLL */ ” and ending with “window.addEventListener(“mousewheel”, H, !1), window.addEventListener(“load”, k, !1));” )