"Requested registry access is not allowed"

Security Exception

Description: The application attempted to perform an operation not allowed by the security policy. To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file.

[SecurityException: Requested registry access is not allowed.]
Microsoft.Win32.RegistryKey.OpenSubKey(String name, Boolean writable) +473

This is caused by an unauthorised user account trying to write to the event log.

MSDN says:

CAUSE

This problem occurs because the user account that you used to log on does not have sufficient permissions.

See: http://support.microsoft.com/default.aspx?scid=kb;en-us;842795