IE7 Intranet zone not accepting FQDN mapped drives

We've recently begun implementing DFS Namespace using FQDN, and I
cannot get our network drives to live in the Intranet zone with IE7.

For example, W:\ is mapped to \\loc.domain.net\share\folder

In IE6, specifying the local Intranet site "*.loc.domain.net" will
place
\\loc.domain.net\share\folder
and
W:\
into the Intranet zone

In IE7, "*.loc.domain.net" doesn't place either in the Intranet zone.
"loc.domain.net" does place \\loc.domain.net\share\folder in the
Intranet zone, but not W:\

I can get W:\ into the Intranet zone by adding "W:\" via the GUI on a
machine with the mapping. This is translated into "file://
loc.domain.net" in the GUI. Exiting options and coming back in, I
cannot delete the entry. I have to remove it from the registry.

What I've discovered is that when typed into the GUI as "W:\", "file://
loc.domain.net" is actually
Key: ZoneMap > Domains > loc.domain.net
Value: file = 1

But when typed into the GUI as "file://loc.domain.net", it becomes
Key: ZoneMap > Domains > domain.net > loc
Value: file = 1

As far as I've been able to determine, I *have* to have the 'Domains >
loc.domain.net' key in the registry to allow the network drives to be
seen as Intranet zone. However, I can't figure out a way to do this
via GPO - other than a reg add script, which I'd rather avoid.

Does anyone have any ideas? Thanks.

PS - I've tried every possible combination of loc.domain.net and file://
and servername I could think of via the GUI, and have read serveral MS
kb's, all to no avail.