When you open a preview or click on the link to open a published report, ScribeWare simply opens your system's default browser that's configured for HTML pages. Sometimes, when Windows runs an update in the background or a new browser is installed, Windows will lose the association, so the preview button will stop responding.
Something similar can happen with PDF and video files. The "open in external editor" simply opens the default application for that file, but if this association gets lost, it can appear as though that button stops working.
Here's a short video to fix this. If you're having trouble with PDF or video files, you'll want to use the relevant file type instead of HTML: