I have a SBS 08 with 50 users on my domain. In Event Viewer : Windows Logs > Security, I've got nearly 300,000 events about EventID 4624 Logon, 4634 Logoff, 4776 Credential Validation, 4769 Kerberos Service Ticket Operations in only... 2 days !!!
I want to simply disable it. I tried disabling the audit in the Local Policy or Group Policy but everything is greyed: Security Settings > Local Policies > Audit Policy > Audit logon events : No Auditing