Have you tried uninstalling the software, restarting the computer fully, then installing it again? That can sometimes take care of odd execution errors like this.
If that doesn't take care of the matter, I'd recommend getting in touch with our support team via the Contact Us form located here: https://support.piriform.com/hc/en-us/requests/new?ticket_form_id=86507 or by emailing support@ccleaner.com - please include information such as when, exactly, the crash occurs, what version of Windows you're using, and any security/antivirus software that may be installed as they may be relevant.