If your JavaScript is broken try the Cache Preset Test CSS first - provided there are no errors try Test JS next. Any reappearing problems with elements (like e.g. a broken slider) are a sure sign for JavaScript errors.
More often than not your problems should be solved by moving JavaScript to the footer (Borlabs Cache > Advanced Settings > JavaScript).
A second common issue is that a themes field for custom JavaScript does contain non valid code e.g.
The theme expects only JavaScript code but often users tend to place HTML code containing JavaScript into the field. This leads to the experienced problems with JavaScript merging.
If that doesn't work for you, there might be a simple error like a missing ; in the JavaScript.
If the problem persists please submit a support ticket.