This problem is specific to your site. It requires a thorough analysis of your site. The reason may be third party plugins you use on your site. Or may be some issue of the Joomla template used on your site. I think it is not the issue of the component IPrice calculator LIGHT. You are the first who faces such a problem.
PS Also I advice you to use the latest version of the component (1.1.28). If you have more old version, then the best way will be to download and install the latest version:
iprice-web.ru/en/products/iprice-light-overview