This Knowledgebase article provides information about Microsoft Windows SharePoint Services Default Web Parts not displaying after a switchover.
With Neverfail for SharePoint installed, after performing a switchover, the SharePoint Default Web Parts do not display and results in one of the following error messages:
This issue occurs when permissions that Windows SharePoint Services configured on the Windows Temp directory were unintentionally reset.
Verify that the permissions for the following folders on the Secondary server match those of the Primary server:
Neverfail for SharePoint v201.5.4
when installed with
Microsoft Windows SharePoint Services 3.0
http://support.microsoft.com/kb/826786 - You receive a cannot deserialize the Web Part error message when you view the SharePoint Services home page