Error: soap:ServerServer was unable to process request. —> 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 SharePoint Designer. 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.
Root Cause:
Some of the web part which you have deployed is causing some problem.
Solution:
you have to remove that webpart..other wise, it will consume some resources and slow down page loads.
How to see unused web parts..
Open IE
http://SP2010/SitePages/Home.aspx?contents=1
here SP2010 is my sharepoint server, change this based on your server name
Once you open above url, it will redirect to one page, where you can see all unused webparts,
this is "Web Part Page Maintenance" page.
Now you can select check box and click on delete
now try to open your site in sharepoint designer...
It will work..
