Group Policy - IE7 Home Page URL

I have an issue with some IE settings from a GPO not applying to Vista. For
testing/isolation, I have an OU with two computers and a single user (Not a
roaming profile). One computer is XP SP2 with IE7 the other Vista Enterprise.
The domain controllers are Windows 2003 R2.

For testing purposes the GPO was created using Vista Group Policy Management
Console with only 2 user settings. One setting disables the screen saver tab
the other setting sets the home page URL in internet explorer.

When I log onto the XP machine for the first time with this user, both
settings are applied. When I log onto the Vista computer for the first time
with the same user, only the screen saver tab is disabled, the IE homepage
url does not change to the GPO setting.

On the Vista computer, running RSoP for the logged in user shows the IE
maintenance setting (homepage URL) from the GPO should be applied. The
'gpresult' command shows the GPO is being applied to the user. The group
policy modelling wizard also shows the URL should change to what is in the
GPO. Logging off and back on several times does not fix it, nor does a
restart. I checked the Group Policy node in the Event Viewer and it only
shows information events, no warnings or errors.

When I run the command 'gpupdate' in Vista and log off and back on the
setting takes effect. Also, when I run 'gpupdate /force' the setting takes
effect immediatley.

Why isn't Vista applying the IE home page url like it should (without manual
commands)? Vista applies other GPO settings fine and XP applies them all
fine.