Starting seeing this on a few clients servers after a recent patch management cycle. It appears to be KB934525 that takes the blame here. After attempting a repair install on one of the systems I eventually found this buried at the bottom of some page that references KB934525. Your application event log will most likely be full of these:
Unknown SQL Exception 33002 occured. Additional error information from SQL Server is included below.
Access to module dbo.proc_getObjectsByClass is blocked because the signature is not valid.
The long and short of it is this: Try running the SharePoint Products and Technologies Configuration Wizard and accept the defaults. If that doesn’t resolve the issue, read on for more…
Post-installation information
After you apply this hotfix package, you must run the SharePoint Products and Technologies Configuration Wizard.To do this, click Start, point to All Programs, point to Administrative Tools, and then click SharePoint Products and Technologies Configuration Wizard.
Important Because of a problem with the hotfix installation, you must not run the SharePoint Products and Technologies Configuration Wizard to complete the installation if you are running a Windows SharePoint Services stand-alone installation that uses the Windows Internal Database Engine. Instead, you must use the Psconfig.exe command-line utility. To do this, follow these steps:
1. Click Start, click Run, type cmd in the Open box, and then click OK.
2. Change to the following directory:
system drive\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\Bin
3. Run the following command:
psconfig -cmd upgrade -inplace b2b
If you ran the SharePoint Products and Technologies Configuration Wizard, you may experience a long delay, and the wizard may not be completed successfully.Alternatively, the configuration process may be unsuccessful, and you may receive the following error messages:
Configuration Failed
An exception of type System.Data.SQLClient.SQLException was thrown. Additional exception information access to module dbo.proc_MSS_GetConfigurationProperty is blocked because the signature is not valid.
Additionally, the following event may be logged in the Application log:Event ID: 5586
Source: Windows SharePoint Services 3
Unknown SQL Exception 33002 occured.
Additional error information from SQL Server is included below.
Access to module dbo.proc_MSS_GetConfigurationProperty is blocked because the signature is not valid.If you experience these issues, use the Psconfig.exe command to manually complete the installation of the hotfix.
–himuraken