Internet Explorer Group Policy Preferences problem

[gwendes]

I accidently set the Security Zones to the default values in Group Policy preferences when I was changing another setting. Didn't noticed the problem on test bed.

This morning this manifested as 'High' for the Internet Zone but after changing it to a lower value (all the users were seeing a lot of security warnings and pages were not loading correctly) now it will not apply anything but a 'Custom' security level even though the policy is applying correctly.

Forced gpupdate.

Tried removing the GPO completely, recreating with the correct settings - nothing seems to actually apply.

Any ideas?

[gwendes]

Manually setting default values corrects the problem, just need a way to ensure that GP is actually making the change that I've instructed it to!