We rolled out the GPO containing the changes outlined and at first it appeared that it worked. Well, it did in a way, our store apps issue was fixed, but our local Windows desktop applications started failing and some of the systems that got the GPO got the dreaded BSOD and others failed to boot after restarting. It appears that the permissions changes destroyed some of the systems access as well. So, while this fix is promising, please tread lightly and do a lot of testing before you proceed. Maybe we missed something, or maybe the policy did a full replace of permissions instead of an appending of new permissions, I don't know. We are still investigating.
Ryan.