NoOST Registry Setting Resets when Group Policy re-applied

We are currently using Outlook 2007 in an Exchange 2007 environment.  The Use Cache Mode feature is greyed out when we try to create a new mail profile on the Outlook client.  We have applied the appropriate Group Policy Outlook 2007 GP Template and changed the following setting to Enabled:

User Configuration/Administrative Templates/Microsoft Office Outlook 2007/Tools | Account Settings/Exchange/Cached Exchange Mode

This didn't seem to rectify the problem.  I did a little more research and found reference to the following registry setting on the client:

HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Outlook\OST\NoOST

References indicate that this should be set to dword value of 0.  My current value is 2.

Further research found the values as follows:
0 - An offline store is set up by default and used for calendar caching. Also, the user is allowed to enable offline access and use the offline store. This is the same as the absence of the OST key and NoOST value.

1 - An offline store is set up by default and used for calendar caching. However, the user is not allowed to enable offline access and use the offline store. The options in the Microsoft Exchange Server properties are not available.

2 - An offline store is not set up by default and the user is not allowed to enable offline access and use the offline store. The options in the Microsoft Exchange Server properties are not available.

3 - An offline store is not set up by default and the user is allowed to enable offline access and use the offline store.

I changed the value to 0.  Unfortunately when I perform a GPUPDATE, the value is again reset to NoOST=dword:00000002.  Does anyone know where in Group Policy, I can set this value to 0 rather than 2.  I just can't seem to find it.

Cheers and look forward to your help.