SharePoint: The trial period for this product has expired.

Method 1:
Go to: http://support.microsoft.com/kb/971620/en-us
(When you install the 2007 Microsoft Office servers Service Pack 2, the product expiration date is activated incorrectly) and follow the document.

Method 2:
Added application pool Account ("dcomcnfg.exe") to the Distributed users
(Add the Application Pool account to the built-in Active Directory group "Distributed COM Users".)
1. Go to Application Pool and see what's the account which can access this Application pool.
2. Go to Active Directory and find the group named "Distributed COM Users". Add the application pool account to that group.