If the web page security validation is turned off, the above error message might be presented when trying to create a document library or list in SharePoint 2010.
To change the setting, log into Central Administration, manage the web app and change the general settings of the web app to enable security validation.
The SharePoint diagnostic tool (SPDiag) is included in the Microsoft SharePoint Administration Toolkit. It comes in handy when analyzing and troubleshooting SharePoint implementations.
Copied from the tothesharepoint blog – http://blogs.technet.com/tothesharepoint/archive/2009/02/05/3197739.aspx:
“With SPDiag, you can:
- Collect IIS and ULS log files, performance counter data, event logs, and WMI instrumentation data from a SharePoint farm.
- Filter data to show granular information related to specific servers, Web applications, HTTP requests, event IDs, URI queries, and almost any other data points captured through supported channels.
- Create custom reports that can help reveal performance trends over time.
- Create snapshots of your SharePoint farm that include detailed information about your farm’s hardware, installed software and logical topology.
- Export collected data and reports that can be sent to Microsoft support personnel.”
Get the toolkit here: