Helpful tip from Clint Denham on the ISAserver.org message boards regarding the "cannot apply configuration changes" problem at: http://forums.isaserver.org/Cannot_apply_configuration_changes_after_install/m_2002008712/tm.htm
This is a common problem and is typically caused by the ’Network Service’ account not having the ’Right’ to ’Generate Security Audits’ in either the Local or Domain policy.
- In AD Users and Computers, go to the Default Domain Policy and select Edit.
- Expand Computer Configuration\Windows Settings\Security Settings\Local Policies, click User Rights Assignment.
- In the right pane, double-click Generate security audits, make sure NETWORK SERVICE and LOCAL SERVICE are listed. If not, add them.
Close Group Policy Object Editor and restart the ISA Server.