Windows 7sp1 IE8 Unable to add to the trusted sites list in Internet Explorer

I have a user who is unable to add websites to their trusted sites list in Internet Explorer. The user's running Windows 7sp1, Internet Explorer 8. I've loaded up a test machine using the same image and configuration that the user has and confirmed that I was able to modify the trusted site list before joining the machine to our domain. After I added the test machine to the domain I was no longer able to modify the trusted sites list, the entire window is grayed out.

The account I'm using has administrative rights on the machine. I've tried running Internet Explorer as administrator and cannot make changes to the trusted sites list. I've looked in:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings

and

HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings

Under "HKCU...\Internet Settings" I've located the Trusted Sites Zone (2) and to avoid confusion and for simplicity sake, tried resetting the Flags value to "2", the setting that should allow me to add trusted sites and I'm still not able to make changes (screen is still grayed out).

In GPEDIT.MSC under Computer Configuration -> Administrative Templates -> Windows Components -> Internet Explorer the setting "Security Zones: Do not allow users to add/delete sites" was set to "Not Configured". I've tried toggling between not configured and disabled and am still not able to add to the trusted sites list.

I'm sure this has something to do with adding the machine to the domain, but I'm not sure what.

Continue reading...