Page not open inside SharePoint Designer ?

Question

Hello,

 

Please tell me when i am going to open the default.aspx page inside SharePoint designer i have got one error.

 

soap:Server Exception of type Microsoft.SharePoint.SoapServer.SoapServerException was thrown. A Web Part or Web Form Control on this Web Part Page cannot be displayed or imported because it is not registered as safe on this site. You may not be able to open this page in an HTML editor that is compatible with Microsoft Windows SharePoint Services, such as Microsoft Office FrontPage. To fix this page, contact the site administrator to have the Web Part or Web Form Control configured as safe. You can also remove the Web Part or Web Form Control from the page by using the Web Parts Maintenance Page. If you have the necessary permissions, you can use this page to disable Web Parts temporarily or remove personal settings. For more information, contact your site administrator.  

 

 

please tell me how to resolve that problem .

 i have added a custom WebPart  inside that page and other page are like Announcement and Event.

 i want to modify that master page but unable to open this page .