The cause is likely the hostname of the server has changed. To fix this, follow the steps below:
1. Open the config.php file, typical location is <server drive>:WebSTATISTICAPub\wwwroot:
2. Change the SoapHost value and click File-->Save:
3. If Data Entry is used, open the web.config file and change the WebSTATHost value (line 67):
4. Click File-->Save to save the updated file.
5. Restart the WebStatistica service
WebStatistica should load the navigation menu.